....at the gym, exercising those muscle and working on joint flexibility! And showing off the results - of course!   

"Don't throw in the towel" - meaning "don't quit just because it is hard work"!  Developing and maintaining fitness IS hard work - but is surely worth that effort. And on the subject of towels - here's a selection that haven't been thrown in, modeled by guys who have most definitely been putting in the work!