I've been doing insanity for a while now. Every day for a few months. Now, a few times a week for the last year or so.
But like anything else, it depends on how hard you push yourself. If you don't push yourself, it won't do much. First time i did Insanity, i puked my guts out.
Entire Team Let Eli down today - NYG4l
By the way, went to the free trial at the gym.
Hated it. Mad ******bags, and I know I won't go there.