Well, today I did this same routine minus the pep I was sweating 15 mins into the workout and dreaded the thought of 30 more mins to go and hated the thought of .... wait what??? Last time I did 10 mins w/ very steep incline, I thought I did 15 last time!!! Ok, I feel soooo good now, I did 15 mins w/ a very steep incline Sheesh, no wonder my legs were burning.
Ok, I did

5 min warm up
30 min fast walking w/ incline
15 min w/ very steep incline
15 mins no incline super fast walking
cool down

My shirt was soaked and I could really feel my abs contracting while walking w/ the incline.

Edit: My 6 year old is obsessed with doing push ups and sit ups lately. He challenged me to a round of both. I did 30 push ups & 50 pilates sit ups. Whew...I broke a sweat.