Yes, some of us became quite lazy and our muscles got flabby. Time to rev it up and work out some and make our butts (that is, glutes) firm and back in good shape again. And that one very good excercise on my pic is called 'Bear Plank Leg Lifts'. Very easy to do and very effective.
Get onboard the fit butt train and don't forget that you can excercise at home or outside in a secluded place (or even streaming on a webcam) while absolutely naked.