Buy some equipment at home, space permitting. Eg: A few pairs of dumbbells, a mat, a pullup bar etc. Let's say you're at your computer doing nerd stuff. You take a bathroom break; do a set of something. You go to the kitchen to get a snack do a set on the way. Etc etc. Curls, squats, lat extensions, whatever.

I say this specifically as someone who hates working out, and as you pointed out, hates the overhead time involved with gyms.