Everyone does, but that seems to involve either a gym membership or owning a barbell set.
Though thinking about my "5 minutes" comment above, I realized I'd forgotten about the Tabata workout routine. I can do push-ups, squats and two sets of kettlebell swings repeated twice in four minutes, and end up feeling like I've had an adequate quick workout. I'll see if I can install this as a habit.
With Alicorn's permission, I'm resurrecting this thread.
I'll start off with one of my own: What kinds of exercise can I do at home (I do have 5- and 20-pound weights), and what are good ways to get motivation to do so regularly?