Depends on multiple things. If I didn't know it was a time loop I would just keep doing the same things over and over in blissful ignorance. If I knew, I would probably do what Cristin Milioti does in Palm Springs - study physics to figure out how to get out of the loop. Besides that, what I did for fun would depend on whether or not I can bring anything with me - like if it's possible to carry a notebook that doesn't get erased I might work on a novel. In any case I would spend significant time dinking around and trying to get laid a lot.