Note to past self: just because you think you can do 100 sit-ups/crunches doesn't make it a good idea to actually try if you've been out of practice for years...unless you like spending an entire work day clutching your sides and wondering if you need to visit the emergency room.

I think I'll stick with "a tenth of Saitama" from now on: 10 push-ups, 10 sit-ups/crunches, 10 squats, and a 1km walk. That should keep my legs, arms, and belly from turning into jelly as long as I keep things up.