Aditattva

Ayurveda means knowledge of the union of body, sense organs, mind and soul. So when people bless saying ‘दीर्घायुषी भव’ (dīrghāyuṣī bhava), it means let person be in union with body, sense organ, mind and soul.

शरीरेन्द्रिय सत्वात्मा संयोगो। – चरक संहिता १।४२
śarīrendriya satvātmā saṃyogo।1.42
The union of Shareera (body), Indriya (sense organs), Satva (mind) and Atma (soul).

ओम धन्वंतरये नमः॥

Dhanvantari, Hindu "God of Medicine" and an avatar of Lord Mahavishnu, mentioned in the Puranas as the god of Ayurveda.

ओम नमो भगवते महासुदर्शनाय वासुदेवाय धनवंतराये:
अमृतकलश हस्ताय सर्वभय विनाशाय सर्वरोगनिवारणाय।
त्रिलोकपथाय त्रिलोकनाथाय श्री महाविष्णुस्वरूप
श्री धन्वंतरि स्वरूप श्री श्री श्री अष्टचक्र नारायणाय नमः॥

सर्वमङ्गलमाङ्गल्ये शिवे सर्वार्थसाधिके ।
शरण्ये त्र्यम्बके गौरि नारायणि नमोऽस्तु ते ॥

Sarvam Mangala Mangalye Shive Sarvaartha Saadhike ।
Sharanye Tryambake Gauri Naaraayani Namostu Te ॥

Auspicious of the auspicious! Parvathi! The fulfiller of the desires!
Protector of all – Three eyed! Parvathi Devi! Narayini! We salute your divinity!!