Exercise Your Right To Plagiarize . . . or Plagiarize Your Right To Exercise?

I often see people doing interesting exercises at the gym-- sometimes with weights, sometimes on the mats, sometimes with unusual equipment, such as medicine balls or rope attachments, and sometimes with the machines and contraptions that I never use-- and whenever I see someone doing an exercise that I've never done before, I have the urge to immediately attempt it, before I forget all about it and go back to my normal routine, but I feel weird about stealing someone's "move" right in front of them, so I always wait until they are out of sight before I copy what they were doing . . . should I feel weird about this?-- about stealing an exercise?-- I probably shouldn't because it's not actually "stealing," as you can't copyright an exercise move . . . or can you?