If I had been in the OP's situation I would have told the guy to go away the first time he tried to talk to me - getting in my space, waving at me and whatnot.
I might have if I hadn't been trying to focus on my running, because it sorta weirded me out how he just stood there watching me, not even using the treadmill he was on. So I finally turned to him when I was in recovery/walking mode to make him go away.
I mean, if his goal was really to hit on me, then dude had no game at all.
It's kinda creepy being stared at like that.
But if it's at a risk of hurting yourself if someone does need to interrupt you for something important, then you're not doing it right. You need to either bring down the intensity level, get instruction for how to use the equipment more safely, or find a different kind of workout.
Right, but even if you're normally very coordinated, all it takes is one slip while running on the treadmill to fall and hurt yourself.
I mentioned upthread that I almost slipped and fell while walking on the treadmill, because I inadvertently stepped partway off the belt. (Fortunately, I managed to catch the railing before I fell and completely embarrassed myself.) That doesn't mean that I'm no longer going to even walk on the treadmill; there is always a risk, no matter how slight, of hurting yourself. [Expletive] happens, after all. I just have an issue with someone unnecessarily increasing that risk by trying to chat me up if it's not necessary. I'm willing to risk it if the gym's on fire, of course.
ETA: And since others have mentioned it, yes, I think the fact that he stood off to the side aggravated the situation.