Bikram Hot Yoga is a therapeutic series of 26 Hatha Yoga postures and 2 breathing techniques, practiced in a room heated to 105 degrees with 40 percent humidity. The series is designed to help improve the condition and physiological systems of the body, and tame the "monkeys" of the mind, thus strengthening the spirit.
This is yoga, NOT to be confused with exercise. Nonetheless, be prepared to sweat and be challenged. With a regular practice, you can change your body and your life. You will immediately feel better, but frequency and consistency are important for the changes to continue and be maintained.