For the resistance training element of things, if you want to firm up your body fast, getting 
a set of adjustable dumbbells is the way to go. By doing 
this I can work out one body part at a time with a 
hundred percent effort and still fully recover to work out my major muscle groups the next week.
I recommend dumbbells for most people who want to maximize 
their P90X workouts and see the most results.