An exercise bike has been great for me. I can pedal while I read, solve a word puzzle, or watch something on YouTube. I often will do my email that way with a computer - I bought a bike with a build-in desktop. (I think it’s called “exer-work” or something like that.)

I also lift weights regularly. I manage to do that by promising myself that I only need to do one set of whatever I feel like lifting. Most of the time I want to do more once I get started, but sometimes I don’t. Setting the bar really low (no pun intended) is how I have managed to form & keep the habit.