Was on a run when I was 15-ish. Mom was at work and my sister was at school so I was totally alone, being that I did high school online at the time other than sports at the local high school. When I was a couple of blocks away I got this really bad feeling like I was being followed but it was like 10 AM so I tried not to think too much about it.
A really bad habit I had post-workout was that, given we were in a rural area, I'd walk around the house without a shirt while making my protein shake and getting ready to soak in our hot tub. While doing these things my dogs started barking wildly but I dismissed it as being some sort of animal in the woods. After about an hour I went upstairs to change, and once again heard my dogs barking at the fence line bordering the woods. When I looked out the window I saw what looked like a man's shoulders and the top of his head facing our house directly in some bushes maybe 10 feet from the fence. After I stood there in horror for a little while he turned around and disappeared into the woods.
I immediately called my mom who called the police, and they checked the woods behind our house and didn't find anything. However when Mom brought it up to some parents in the area, some said their sons also reported a creepy older dude following them in those woods and on the outskirts of the high school grounds. Needless to say I switched to running on our treadmill for a long time, and made a habit of keeping all of our blinds closed. Was pretty terrified of this guy like breaking into the house and coming after me, too, so for a long time I kept my pocket knife on me at all times and walked around the house with my gas-powered BB gun.