Good on you for doing that. I did the same thing when I was in college, but in my case, I did it to get better at approaching women.

I made it a goal to talk to at least one woman per day on the train in NYC (hard mode) and say Hi to at least three.

I don't remember how long I kept this up for; I want to say I did this for three months, but it might have been shorter.

Like you, some people wanted nothing to do with me while others were down to chat.

While this made it easier for me to make the first move, it helped me massively at starting and keeping up conversations with anyone about nearly anything. This is probably a large reason why I'm in tech sales these days.

That being said, this didn't change my default personality. I'm still very introverted, very comfortable with hanging out by myself, have trouble not taking rejection personally (though I'm much better at this than I was back then), and, most importantly, absolutely hate talking to people at the gym, almost all of the time!

(My workouts are 90-120 minutes long on most days, which is a huge chunk of time that I'd rather spend coding, working or catching up on HN/Reddit. I immediately think of how much time I'm sacrificing whenever I'm approached at the gym and stonewall. I'm also like this on airplanes. The joys of constantly feeling behind and stressed for time!)