Me and my friend have thought about P90X though it's really advanced (p90 will probably be way better for some) it's basically muscle confusion and eating healthy with some muscle drinks added in. Like SoxFan562004 said, you have to mix it up cause if your body gets used to the same routine, you won't get the quicker results. P90X pushes you beyond your breaking point. Say you can only do 20-30 pushups they'll make you push that into 40-50 they constantly challenge you. Switch up your routine each week (do straight push-ups one week, do push-ups with a chair or one handed the next week, etc..) and you'll be fine. The motivation is always the hard part. I have ZERO weights at home, (ok I see like 5 lb dumbells but thats it) so I find it hard to do anything anyway, and pushups help tone your arms, but I do want alittle more muscle developed.