Originally delivered to this world by highly adept and balanced beings, yoga is a means of physical, psychic, and vibrational self cultivation, through esteemed and honorable engagement with the movements of the cosmos.
The practice of yoga enhances every quality we need to stay vigorously healthy beyond even the standards of that which we call modern medicine---immunity to disease, rapid healing, resistance to toxins, strength, flexibility, poised movement, muscle tone, and control. Going even further than modern medicine in combination with asana, the discipline of breath through pranayama cleanses, conditions, and enforces the nervous system, empowering it, so that when we incounter difficulties in life, our free will has a higher impact on our own internal experience. The rest of it is up to your personal choice of attitude, self accountability, dedication, determination, devotion, and focus. Regardless of age, beliefs, or physical condition, any competent yogic practice will be fully beneficial, harmless, customised, and therapeutic.