P90X is a great, well rounded program. It also has the most difficult and useful 90 minutes of yoga I've seen anywhere. Another excellent alternative is http://www.crossfit.com/. Different people have different results with different programs, depending on their relative fitness levels and slews of other factors. P90X is a fantastic place to start for anyone with a reasonable level of fitness, while crossfit or similar programs are geared towards those in better shape. Which isn't to say that P90X is a slouch program by any means. It will kick most people's ass pretty thoroughly, though I don't think I could recommend the accompanying diet unless you're in horrible shape.