Three Kinds of Treatment Modalities according to Charaka Saṁhitā:

त्रिविधमौषधमिति- दैवव्यपाश्रयं, युक्तिव्यपाश्रयं, सत्त्वावजयश्च| तत्र दैवव्यपाश्रयं- मन्त्रौषधिमणिमङ्गलबल्युपहारहोमनियमप्रायश्चित्तोपवासस्वस्त्ययनप्रणिपातगमनादि,युक्तिव्यपाश्रयं- पुनराहारौषधद्रव्याणां योजना, सत्त्वावजयः- पुनरहितेभ्योऽर्थेभ्यो मनोनिग्रहः||५४||
trividhamauṣadhamiti- daivavyapāśrayaṁ, yuktivyapāśrayaṁ, sattvāvajayaśca| tatra daivavyapāśrayaṁ-mantrauṣadhimaṇimaṅgalabalyupahārahōmaniyama-prāyaścittōpavāsasvastyayana-praṇipātagamanādi,yuktivyapāśrayaṁ- punarā hārauṣadhadravyāṇāṁ yōjanā, sattvāvajayaḥ- punarahitēbhyō’rthēbhyōmanōnigrahaḥ||54||

“There are three kinds of treatment modalities- Daivavyapashraya (divine or spiritual therapy), yuktivyapashraya (therapy based on reasoning) and satwavajaya (psychotherapy). 

Daivavyapashraya includes mantra chanting, medicine, wearing gems, auspicious offerings, oblations, gifts, offerings to sacred fire, following spiritual rules, atonement, fasting, chanting of auspicious hymns, obeisance to gods, visit to holy places, etc. 

Yuktivyapashyraya includes proper dietetic regimen, medicine planning. 

Sattvavajaya is withdrawal of mind from harmful objects.” [54]

Karmic Disease Quotes from Charaka:

Disease from a Previous Birth according to Charaka Saṁhitā:

परिहार्याण्यपथ्यानि सदा परिहरन्नरः| भवत्यनृणतां प्राप्तः साधूनामिह पण्डितः||४३||
यत्तु रोगसमुत्थानमशक्यमिह केनचित्| परिहर्तुं न तत् प्राप्य शोचितव्यं मनीषिभिः||४४||
parihāryāṇyapathyāni sadā pariharannaraḥ| bhavatyanr̥ṇatāṁ prāptaḥ sādhūnāmiha paṇḍitaḥ||43||
yattu rōgasamutthānamaśakyamiha kēnacit| parihartuṁ na tat prāpya śōcitavyaṁ manīṣibhiḥ||44||

One should always avoid unwholesome food. If one gets afflicted with a disease despite leading a healthy lifestyle, then he is not at fault as it could be the effect of previous birth. [1.28.43-44]

If you live a Healthy Life and Get Sick Anyway:

सत्याश्रये वा द्विविधे यथोक्ते पूर्वं गदेभ्यः प्रतिकर्म नित्यम्| जितेन्द्रियं नानुपतन्ति रोगास्तत्कालयुक्तं यदि नास्ति दैवम्||४३||
satyāśrayē vā dvividhē yathōktē pūrvaṁ gadēbhyaḥ pratikarma nityam| jitēndriyaṁ nānupatanti rōgāstatkālayuktaṁ yadi nāsti daivam||43||

Even though the above mentioned two-fold seats of diseases (body and mind) exist, one who always takes precautions against diseases and has control over the senses does not fall prey to diseases except when predestined. ||4.2.43||

दैवं पुरा यत् कृतमुच्यते तत् तत् [२८] पौरुषं यत्त्विह कर्म दृष्टम्| प्रवृत्तिहेतुर्विषमः स दृष्टो निवृत्तिहेतुर्हि समः स एव||४४||
daivaṁ purā yat kr̥tamucyatē tat tat [28] pauruṣaṁ yattviha karma dr̥ṣṭam| pravr̥ttihēturviṣamaḥ sa dr̥ṣṭō nivr̥ttihēturhi samaḥ sa ēva||44||

The deeds of the previous life are known as daiva (fate) and those of the present life as paurusha (personal effort). Imbalance of these (daiva and paurusha) leads to diseases and balance prevents the diseases||4.2.44||

Prajnapradha may be due to negative actions of the Past Life: 

तमुवाच भगवानात्रेयः- सर्वेषामप्यग्निवेश! वाय्वादीनां यद्वैगुण्यमुत्पद्यते तस्य मूलमधर्मः, तन्मूलं वाऽसत्कर्म पूर्वकृतं; तयोर्योनिः प्रज्ञापराध एव| तद्यथा- यदा वै देशनगरनिगमजनपदप्रधाना धर्ममुत्क्रम्याधर्मेण प्रजां वर्तयन्ति, तदाश्रितोपाश्रिताः रजनपदा व्यवहारोपजीविनश्च तमधर्ममभिवर्धयन्ति, ततः सोऽधर्मः प्रसभं धर्ममन्तर्धत्ते, तस्तेऽन्तर्हितधर्माणो देवताभिरपि त्यज्यन्ते; तेषां थाऽन्तर्हितधर्मणामधर्मप्रधानानामपक्रान्तदेवतानामृतवो व्यापद्यन्ते; तेन नापो यथाकालं देवो र्षति न वा वर्षति विकृतं वा वर्षति, वाता न सम्यगभिवान्ति, तिर्व्यापद्यते, लिलान्युपशुष्यन्ति, ओषधयः स्वभावं परिहायापद्यन्ते विकृतिं; तत उद्ध्वंसन्ते जनपदाः श्याभ्यवहार्यदोषात् ||२०||
tamuvāca bhagavānātrēyaḥ- sarvēṣāmapyagnivēśa! vāyvādīnāṁ yadvaiguṇyamutpadyatē tasyamūlamadharmaḥ, tanmūlaṁ vā’satkarma pūrvakr̥taṁ; tayōryōniḥ prajñāparādha ēva|

Lord Atreya replied that the root cause of vitiation of these factors is adharma (unrighteousness). Sins of the present life or the misdeeds of the past life also are at the root of vitiation of all these factors and the source of this is intellectual error (prajnaparadha). [3.3.20]

Disease from the Past Life:

एते चान्ये [६] च ये केचित् कालजा विविधा गदाः| अनागते चिकित्स्यास्ते बलकालौ विजानता||११४||
ētē cānyē [6] ca yē kēcit kālajā vividhā gadāḥ| anāgatē cikitsyāstē balakālau vijānatā||114||

A physician acquainted with the knowledge of dosha bala and kala bala should treat this and other similar diseases prior to their actual manifestations. [114]

कालस्य परिणामेन जरामृत्युनिमित्तजाः| रोगाः स्वाभाविका दृष्टाः स्वभावो निष्प्रतिक्रियः||११५||
kālasya pariṇāmēna jarāmr̥tyunimittajāḥ| rōgāḥ svābhāvikā dr̥ṣṭāḥ svabhāvō niṣpratikriyaḥ||115||

The diseases arising out of temporal factors that bring about old age and death are to be considered as natural ones, which affect everyone, and these such natural manifestations are irremediable. [115]

निर्दिष्टं दैवशब्देन कर्म यत् पौर्वदेहिकम्| हेतुस्तदपि कालेन रोगाणामुपलभ्यते||११६||
nirdiṣṭaṁ daivaśabdēna karma yat paurvadēhikam| hētustadapi kālēna rōgāṇāmupalabhyatē||116||

The deeds performed in the previous life or past time are known as daiva (fate) also constitutes in due course causative factors for the manifestation of diseases. [116] In other words it could be also said that some causes do not produce disease at the same time because they have less strength (karmaja roga).

न हि कर्म महत् किञ्चित् फलं यस्य न भुज्यते| क्रियाघ्नाः कर्मजा रोगाः प्रशमं यान्ति तत्क्षयात्||११७||
na hi karma mahat kiñcit phalaṁ yasya na bhujyatē| kriyāghnāḥ karmajā rōgāḥ praśamaṁ yānti tatkṣayāt||117||

There is no such major action/deed (performed in the previous life/past time) which does not lead to the corresponding results. Diseases arising out of such actions/deeds are not amenable to any therapeutic measures. They are cured only after the effects of past actions/deeds are exhausted i.e. fully enjoyed. [117]

Past Life Karma impacts present Physiology: 

भूतैश्चतुर्भिः सहितः सुसूक्ष्मैर्मनोजवो देहमुपैति देहात्| कर्मात्मकत्वान्न तु तस्य दृश्यं दिव्यं विना दर्शनमस्ति रूपम्||३१||
bhūtaiścaturbhiḥ sahitaḥ susūkṣmairmanōjavō dēhamupaiti dēhāt| karmātmakatvānna tu tasya dr̥śyaṁ divyaṁ vinā darśanamasti rūpam||31||

The soul, along with four subtle bhutas, at a speed like that of the mind, transmigrates from one body to the other according to past deeds. It cannot be seen without divine visual sense. ||4.2.31||

स सर्वगः सर्वशरीरभृच्च स विश्वकर्मा स च विश्वरूपः| स चेतनाधातुरतीन्द्रियश्च स नित्ययुक् सानुशयः स एव [१६] ||३२||
sa sarvagaḥ sarvaśarīrabhr̥cca sa viśvakarmā sa ca viśvarūpaḥ| sa cētanādhāturatīndriyaśca sa nityayuk sānuśayaḥ sa ēva [16] ||32||

The soul is omnivagant/ omnipresent (can move anywhere and everywhere), sustains all bodies, performs all actions, and takes all forms. It is the source of consciousness, transcending all senses, as it is always associated (with intellect etc.), it gets involved in attachment etc.||4.2.32||

रसात्ममातापितृसम्भवानि भूतानि विद्याद्दश षट् च देहे| चत्वारि तत्रात्मनि संश्रितानि स्थितस्तथाऽऽत्मा च चतुर्षु तेषु||३३||
rasātmamātāpitr̥sambhavāni bhūtāni vidyāddaśa ṣaṭ ca dēhē| catvāri tatrātmani saṁśritāni sthitastathātmā ca caturṣu tēṣu||33||

In the body, the bhutas are sixteen (each set of four bhutas is of four types), originating from maternal nutrition, the self, mother (ovum) and father (sperm). Out of these, four are associated with the self and the self, in turn, depends on these four.||4.2.33||

भूतानि मातापितृसम्भवानि रजश्च शुक्रं च वदन्ति गर्भे| आप्याय्यते शुक्रमसृक् च भूतैर्यैस्तानि भूतानि [१७] रसोद्भवानि||३४||
bhūtāni mātāpitr̥sambhavāni rajaśca śukraṁ ca vadanti garbhē| āpyāyyatē śukramasr̥k ca bhūtairyaistāni bhūtāni [17] rasōdbhavāni||34||

The bhutas from the mother and the father are known as ovum and sperm in the fetus respectively. The bhutas which nourish these sperm and ovum are nourished from the mother’s nutrition. ||4.2.34||

भूतानि चत्वारि तु कर्मजानि यान्यात्मलीनानि विशन्ति गर्भम्| स बीजधर्मा ह्यपरापराणि देहान्तराण्यात्मनि याति याति||३५||
bhūtāni catvāri tu karmajāni yānyātmalīnāni viśanti garbham| sa bījadharmā hyaparāparāṇi dēhāntarāṇyātmani yāti yāti||35||

रूपाद्धि रूपप्रभवः प्रसिद्धः कर्मात्मकानां मनसो मनस्तः| भवन्ति ये त्वाकृतिबुद्धिभेदारजस्तमस्तत्र च कर्म हेतुः||३६||
rūpādhi rūpaprabhavaḥ prasiddhaḥ karmātmakānāṁ manasō manastaḥ| bhavanti yē tvākr̥tibuddhibhēdārajastamastatra ca karma hētuḥ||36||

अतीन्द्रियैस्तैरतिसूक्ष्मरूपैरात्मा कदाचिन्न वियुक्तरूपः| न कर्मणा नैव मनोमतिभ्यां न चाप्यहङ्कारविकारदोषैः||३७||
atīndriyaistairatisūkṣmarūpairātmā kadācinna viyuktarūpaḥ| na karmaṇā naiva manōmatibhyāṁ na cāpyahaṅkāravikāradōṣaiḥ||37||

रजस्तमोभ्यां हि मनोऽनुबद्धं ज्ञानं विना तत्र हि सर्वदोषाः| गतिप्रवृत्त्योस्तु निमित्तमुक्तं मनः सदोषं बलवच्च कर्म||३८||
rajastamōbhyāṁ hi manō’nubaddhaṁ jñānaṁ vinā tatra hi sarvadōṣāḥ| gatipravr̥ttyōstu nimittamuktaṁ manaḥ sadōṣaṁ balavacca karma||38||

It is not all genetics:

यच्चोक्तं- यदि च मनुष्यो मनुष्यप्रभवः, कस्मान्न जडादिभ्यो जाताः पितृसदृशरूपा भवन्तीति; तत्रोच्यते-यस्य यस्यह्यङ्गावयवस्य बीजे बीज भाग उपतप्तो भवति, तस्य तस्याङ्गावयवस्य विकृतिरुपजायते, नोपजायते चानुपतापात्;तस्मादुभयोपपत्तिरप्यत्र| सर्वस्य चात्मजानीन्द्रियाणि, तेषां भावाभावहेतुर्दैवं; तस्मान्नैकान्ततो जडादिभ्यो जाताः पितृसदृशरूपा भवन्ति||१७||
yaccōktaṁ-yadi ca manuṣyō manuṣyaprabhavaḥ, kasmānna jaḍādibhyō jātāḥ pitr̥sadr̥śarūpā bhavantīti;tatrōcyatē-yasya yasya hyaṅgāvayavasya bījē bīja bhāga upataptō bhavati, tasya tasyāṅgāvayavasyavikr̥tirupajāyatē, nōpajāyatē cānupatāpāt; tasmādubhayōpapattirapyatra| sarvasya cātmajānīndriyāṇi, tēṣāṁ bhāvābhāvahēturdaivaṁ; tasmānnaikāntatō jaḍādibhyō jātāḥpitr̥sadr̥śarūpā bhavanti||17||

So, the answer to the previous question “if the human being is a product of another human being, why is a progeny of a dull human being not always dull?” is that, if the part of the seed (sperm or ovum) responsible for the development of a specific organ is afflicted, the respective organ will be afflicted too. However, if the seed is not afflicted, there would be no affliction of the respective organ. So both the possibilities are there. In fact, the sense organs of all the living beings are derived from the soul and their presence or absence is determined by fate caused by past life actions (daiva). So the offspring of dull parents do not necessarily resemble their parents in those qualities. [4.3.17]

Like a damn stops a returning flood, protect from future disease: 

cikitsati bhiṣak sarvāstrikālā vēdanā iti| yayā yuktyā vadantyēkē sā yuktirupadhāryatām||86||
punastacchirasaḥ śūlaṁ jvaraḥ sa punarāgataḥ| punaḥ sa kāsō balavāṁśchardiḥ sā punarāgatā||87||
ēbhiḥ prasiddhavacanairatītāgamanaṁ matam| kālaścāyamatītānāmartīnāṁ punarāgataḥ||88||
tamartikālamuddiśya bhēṣajaṁ yat prayujyatē| atītānāṁ praśamanaṁ vēdanānāṁ taducyatē||89||
āpastāḥ punarāgurmā yābhiḥ śasyaṁ purā hatam| yathā prakriyatē sētuḥ pratikarma tathāśrayē||90||
pūrvarūpaṁ vikārāṇāṁ dr̥ṣṭvā prādurbhaviṣyatām| yā kriyā kriyatē sā ca vēdanāṁ hantyanāgatām||91||
pāramparyānabandhastu duḥkhānāṁ vinivartatē| sukhahētūpacārēṇa sukhaṁ cāpi pravartatē||92||
na samā yānti vaiṣamyaṁ viṣamāḥ samatāṁ na ca| hētubhiḥ sadr̥śā nityaṁ jāyantē dēhadhātavaḥ||93||
yuktimētāṁ puraskr̥tya trikālāṁ vēdanāṁ bhiṣak| hantītyuktaṁ cikitsā tu naiṣṭhikī yā vinōpadhām||94||

The following logic is given here while responding to the question on the management of illnesses of the past, the present and the future. Recurrence of headache, fever, cough and vomiting establishes the fact that diseases of the past do relapse. That is to say, the time of occurrence of the various diseases in the past repeats itself. The therapeutic devices meant for alleviating such recurring diseases verily take the past history (of such diseases) into consideration.

In order that flood waters may not damage crops as they did in the past, a dam is constructed as a preventive measure. So are some therapeutic devices prescribed to prevent certain diseases which are likely to attack living beings in future. This treatment relates to prevention of future diseases.

A continuity of ailments is checked by treatments that are conducive to the continuity of happiness. The state of equilibrium of dhatus is not disturbed nor is the imbalanced state brought to normalcy without some causative factors. It is the causative factors which determine the equilibrium or imbalance of the dhatus. So a physician treats the diseases pertaining to the past, present and future. [4.1.86-94]

The Āyurvedic text, Bhāvaprakāśa of Bhāvamiśra (6.48), mentions an astrologer (daivajña) as a person not to approach with empty hands:

तथाहि-रिक्तहस्तो न पश्येत्तुराजानं भिषं गुरुम् | दैवज्ञं देवतां मित्रं फलेन फलमादिशेत् ||
tathāhi-riktahasto na paśyetturājānaṁ bhiṣajaṁ gurum | daivajñaṁ devatāṁ mitraṁ phalena phalamādiśet ||

The king, physician, preceptor, astrologer, gods and friends, should not be approached with empty hands, meeting them with some fruits in hand yields fruit (bestows good luck).