This is a boring personal exercise post so skip if you think that's as horrible as it sounds.
I've been an on-again-off-again runner (fast jogger, whatever) since my mid-20s. More off than on, but with periods of being on and getting in pretty good shape. Back when I was young and beautiful I could do a 5K in an almost respectable time, and I've done a couple of half marathons/10 milers at a somewhat better than waddling pace.
I'm defining "in shape" in terms of having some decent cardiovascular endurance, not being skinny and ripped. Anyway, after being mostly off for a few years I've been back on (imperfectly, as these things go, but still) for a year or so. And getting "back" in shape... is...uh, hard. Younger me mocks my 5k time, but more than that... improvements are very very slow, and I actually have been putting in a lot of miles.
Just getting around to the point that this shit was easier when I was younger. It's harder now. Best not to lose it because it's harder to get it back.
tl;dr getting old sucks
