It's all about mindset:
1) I act as if I literally own the gym, and act accordingly, gracious but with some degree of pride. MC of the Party. I am on great terms with all of the staff, as I am one of the longest-standing members, and in terms of overall fitness, one of the best examples they could ever hope for (probably overall literally the fittest man in the U.S. for my age who doesn't do test or other PEDs).
2) I act as if I have already had relations with every woman in the venue, so sex is no longer a big deal between us. I give them little tasks like handing me a plate as I am racking up, compliment them after they comply.
Once we do hook up, and often it is later discontinued for whatever reason (she wants me to be her exclusive boyfriend, jealousy of other girls, etc,) it is up to her to deal with it. After all, SHE came into MY gym :) I am cordial to everybody, but since I am upfront in my demeanor and intent from the first move, any "blowback" is minimized and actually rather cute as far as I'm concerned. Of course I am careful and have avoided any drama with STIs or pregnancy, etc.. If you can't handle your business properly along these lines, you have no business dating anyway, stick to your online porn.
Yes, I'm a dicck, but not an A-hole, I love 'em all, and the dudes are cool until proven otherwise. No games, no aplologies, no problems. I made many many mistakes over the years, to arrive where I am, but avoided many more. The chances of any random runners doing this are 0.000001%