Yoga is a great way to keep ourselves happy and healthy. While Asanas or physical postures help our bodies be flexible and disease free, pranayama and meditation takes us to the higher goals of peace and harmony.
However, yoga is not a magic pill that can be done for a few days or months and expect a miracle to happen. Yoga requires continuous lifelong sadhana. When a practice becomes perseverance, has passion and devotion in it, then it becomes Sadhana.
Swami Vivekanada says:
Take up one idea. Make that one idea your life - think of it, dream of it, live on that idea. Let the brain, muscles, nerves, every part of your body, be full of that idea, and just leave every other idea alone. This is the way to success, that is way great spiritual giants are produced
Do you practice yoga regularly as a sadhana? Please check with your doctor before practicing yoga.