I had to put this to the test today. 20 minutes on the bike is pretty much my limit. I've tried to push myself to go longer but it just doesn't happen. So with this saying in mind I watch 2 episodes on Netflix instead of one. Amazing. . . . 40 minutes felt no different then with 20. O.K. My back hurts, but that's just because my bike seat is horrible. But for my knee and the rest of me. . . . 40 minutes was doable.
I'll have to see how first thing Saturday morning compares to after working all day. I'll give it a try Monday and let you know how it goes.