In an several earlier books it was referenced that wizards heal completely unlike us normal mortals. with this complete healing harry should never feel the minor pains of ageing that mortals feel because his body can fully heal from all the strains and damage done to it. If this is the case why did he feel so good without a body being absolutly free from all the small nagging pains of getting older that we tend to ignore? he should not have had any except for current battle damage.
"Healing fully" and "healing instantly" aren't the same thing.
I mean, sure, if Harry were to take a year or two off and take good care of himself, he'd get back to "fine". But as a big guy, he's constantly dealing low level damage to his knees, or to his back, for example. His wizard healing will be working pretty much constantly just to mitigate the damage.
