Celebrity Sighting?

I'm not good with faces. Or names for that matter. It's the perfect storm. But sometimes I'll be working out at the gym or walking down the street and think I see a celebrity, but I'm never all that sure since they look smaller, skinnier, and older. So I'll try to stare through my sunglasses or over my shoulder, but the person always notices me looking and I turn away as quick as I can. But then a moment later I'm back to looking again. Not that I'd ever walk up or ask for an autograph or anything, I just want to know if John Stamos is working out at my gym. If it's not him, then it's a pretty depressing state that I'm staring at a guy who kind of looks like John Stamos.