I'm with Rhonda, I didn't do any running on this one, but it killed me! I made it into a good power walking workout and maintained 4.0 mph for the entire workout and went to 10% incline on all the hills. That was really tortuous (for me) on challenge 2. Though I'm not crazy about an all hill workout, this will be good to toss into the mix. And the music is awesome!!!!!!!!!