I was on the treadmill at the gym and I was suddenly thrust and tortured into a conversation without an escape route

I was 11 minutes in and minding my business on the treadmill and someone got on the next one and suddenly and without warning started talking to me. I had no idea what to say or how to conveniently escape the situation. I listened politely, smiled appropriately, and nodded reassuringly as if on cue. I wasn't prepared for this and when the person finally left, I was so exhausted not from the treadmill but being held hostage like that.

He said he had seen me around and it was nice to finally meet. I'm not sure what he meant exactly or what his intentions were, but it felt like an intrusion. Later on, I got a dirty look from that trainer I had a run-in a few months ago who forced me off a machine I had been waiting for. Both incidents combined, it was a real ambush.