Yeah, I'm well aware. I've got two now, and had an Aussie earlier. I'd do things like hide mail around the house for her to find and gather, since that was one of her jobs. She'd bring me my shoes in the morning, get the mail for me, that kind of thing.
But if you don't even have a yard to exercise them, it's downright impossible. They don't really require that much effort, in my experience. Gotta play with them, and have tasks for them to do. Otherwise they go straight insane, and can either tear up your place, or hurt themselves. But you're talking about really minimal effort. It doesn't take all that much time to keep them occupied.
They're a great candidate for Go, Dog, Go (that automatic ball-throwing machine that dogs can use on their own). Downside is that they might actually do it constantly, all day, every day, and that's actually really bad for them.