What goes through men's minds when they stare or glance repeatedly at a woman they find attractive?

I never fantasize about real-life people. It feels like I'm doing an injustice to them. When I see a woman I'm attracted to, usually I think, "Gosh, she's beautiful." I would have no illusions about her accepting me, so I wouldn't bother thinking about it. You can't stare at her for too long after that.