Yoga has multiple benefits.
As many have already mentioned, it increases your flexibility, tones your muscles and builds your strength. I started yoga because I had severe health issues including chronic fatigue syndrome, fibromyalgia, insomnia, PCOS, depression and panic disorder. I suffered from these for 10 years (through my mid 20s to my 30s) and the symptoms were so debilitating that I was often bedridden for months at a time. I had tried every branch of medicine I could think of - neurology, endocrinology, psychiatry etc.The doctors couldn't figure out what was wrong with me, much less help me. When conventional medicine didn't help, I tried ayurveda and homeopathy. Nothing helped. Finally, I decided to give yoga a try. I started yoga more because I felt I had exhausted every other option, than from any real belief in the healing power of yoga. After my first class, I felt calmer, the stretching helped my body pain and the breathing helped with my energy. I decided to go again.