This website (from bodyrock.tv), explains how to become a bodyrocker - A person who does intense short workouts at home for free (which is a new fitness movement). I love this fitness idea because the workouts are short (which means you don't have an excuse not to do them), but they burn as much calories as if you were to go to the gym and kind-of workout for 1.5 hrs.
All you need to do is increase by 10 every 3 days .. You will really feel your ass the next day !!! AMAZING. Running doesn't do anything for your butt, just makes you more aware of the fact that it's wobbly!!!!
(Another pinner said: This website is AMAZING. It is my workout bible, and best of all, its completely FREE. Tons of workout vids and plenty more to stave off ruts. Most of the routines are between 12-20 mins long and that's all you need.)