Since May 2005, I have been teaching myself yoga from home 2-3 times per week using a DVD, mostly. My life of chronic back pain is coming to a close as a result and my body is getting definition and strength back that I never thought I'd have.
Because yoga (particularly this style I'm learning, Ashtanga Yoga) heats the body from the inside out, it does a great job of cleansing and detoxing, too. Sometimes this leads to a feeling just a little worse 12-24 hours after a practice session. But this always clears and then I end up feeling tremendous physically, which of course helps a bit mentally as well, although I am learning yoga purely for the physical benfits.
The fact that I can make so much progress physically with 40 mins of workout only 2-3 times per week makes yoga my ideal exercise. As a father of 3 kids under 6 years of age, and one on the way, I don't have a lot of time to be out of the house at the gym right now. So it's one of the most efficient uses of my workout minute, if you will.
I'll post more on this over time because I'd love for my friends to pick up on it as well and avail themselves of some of the same physical gains.