One of the most powerful and quitessential forms of exercise that requires intense mental concentration. When practiced correctly and concentrating on breathing, yoga increases flexibility, muscle definition, endurance, and mental clarity. Yoga is not for the physically or mentally weak. Anyone who downplays the effectiveness of yoga or says anything negative about it should be mercilessly beaten.
I do yoga for the following reasons: it increases my flexibility so I can do wierd shit and not get injured in sports, it increases my endurance, it increases my definition (it's how I got a six pack), and girls think it's hot.