I just don't get it. I'm not in bad shape; size 10, BMI 21, have a very active lifestyle, lots of walking, squats, lunges, cycling etc. But no matter what I do, the bum stays resolutely saggy. Is it an age thing (am 39)? Or a genetically determined body shape issue? If anyone can tell me a non-surgical way to lift the old arse a couple of cms off the back of my thighs, I will buy them a pint. Honest.