Being sociable ≠ Being annoying/creepy

That's all about intent. You gauge a response using body language. My gym has a racquetball court. I get asked to play all the time by random people. Be friendly and people will come to you. I had a problem with facial expressions growing up and I worked on mirroring. I mostly do it without thinking these days but it didn't start that way.

You can meet people at the gym. General rule is don't be disruptive.