I really don't see the problem with meeting someone at the gym. It just another place you can meet someone.
No question the point of the going to the gym is to work out, but if the opportunity is available give it a shot. We are busy people who don't have a ton of time so why not give it a shot. I don't mean bug women while they are working out, but if you see someone you like throw them a smile when you make eye contact. If she smiles back then maybe take that as invite for a little chat between sets. Also if you are working out at a similar time every day you start to see the same people all the time. In that case my best pickup line is "Hi" with a smile as you are walking pass.
I love talking to women at the gym because you have a similar interest available. "Working out"