Stairmill x 30 minutes
Over the course of 1,800 seconds - you have the opportunity to innovate.
I started doing this yesterday. Instead of walking head on up the stairs, I crossed my feet over stepping to the far left with my right foot, and to the far right with my left foot. It did require paying more attention, so as not to fall off the stairmill... but it was definitely using muscles that don't usually get called into action -- and that is a big part of what I am trying to do. Waking up and using muscles that haven't been developed.
In addition, I was going through 30 second bouts of taking every other step and changing the speed (level) to keep my heart rate up and me on my toes.
Then, 16 minutes on the treadmill. Never did get into a groove there, but did enjoy my last 14 minutes on the bike before calling it a day.
Tomorrow may be a day of rest, or if I wake up and feel like I have the energy, it will be Day 5.