Bhagavad Gita 6.16–17

Yoga is not for one who overeats or who starves, nor for one who sleeps too much or never sleeps. For the one whose food, movement, work, sleep and waking are measured, yoga becomes the destroyer of sorrow.

नात्यश्नतस्तु योगोऽस्ति न चैकान्तमनश्नतः ।
न चातिस्वप्नशीलस्य जाग्रतो नैव चार्जुन ॥
युक्ताहारविहारस्य युक्तचेष्टस्य कर्मसु ।
युक्तस्वप्नावबोधस्य योगो भवति दुःखहा ॥

natyashnatas tu yogo ’sti na caikantam anashnatah |
na catisvapnashilasya jagrato naiva carjuna ||
yuktahara-viharasya yukta-ceshtasya karmasu |
yukta-svapnavabodhasya yogo bhavati duhkhaha ||

Yoga is not for one who overeats or who starves, nor for one who sleeps too much or never sleeps. For the one whose food, movement, work, sleep and waking are measured, yoga becomes the destroyer of sorrow.

This verse shows exactly why physical habits are the foundation of mental health. What you do with your physical body—how much you eat, sleep, and move—directly controls how your mind feels. You cannot achieve mental peace if you neglect your basic physical needs. A steady, balanced daily routine is your strongest defense against stress and emotional sorrow.