Two scenarios. Tried to add a bit of randomness to it.

The gym was... difficult. Recently something had actually convinced you to buy a gym membership. Your nearby gym wasn't some grand architect, didn't have the best equipment, and wasn't extravagantly big. But it was close to home. The past 3 miles of jogging had you forgetting why you joined, and looking around, it deffenetly wasn't the people. This treadmill was the first workout, but you already felt like you were either about to pass out or explode.

You heard the machine next to you whir up, and someone begin running. You raised your head and... your face started to heat up a bit. Maybe it was a little bit because of the people.