"What ... that I took care of myself?" Harry quirked, lightly. "There's a causal link between physical health and magical potency, you know. I got into the habit in Germany. Dietmar was an Olympic-level demon on the gymnastic rings. Built like a brick shithouse, to boot. I'm too sinewy for all that, but I get my wiry arse as trim as I can. I cheat, obviously, through mediation and yoga rituals. But it works well enough."