I dislike setting aside specific time for lifting weights (and weight training in general) but wouldn't mind some added definition and arm size with realistic expectations for only getting whatever I put into it. I notice I don't find it as annoying if I do about 8-12 mini-workouts a day. When I say mini I mean no more than a couple minutes, as a break from whatever I am doing at the time.
This could be anything from 2 sets of 30 leg-elevated pushups, to as many pullups I can do in 2 or 3 sets, to a couple sets of curls, or bent-over rows or whatever. Every hour or two, when I find a moment.
I'm very aware this isn't optimal. But is it totally useless? Aside from gaining a little strength, will I see even remote size increase or reasonable definition over time if I keep adding difficulty to the exercises as I adapt?