If I think about my devolution to out of shape middle aged guy, cardio was the first thing to suffer. I never liked it, even when I would run 10K in about an hour, which is not that impressive, I know, but that was as a heavy guy (even then). I always liked lifting weights, it gave just the right kind of biochemical/stress-relief reaction that I could spend a couple of hours in the evening doing pretty strenuous sets. I'm not sure if diet went after or actually started well before. I've never really watched what I ate except for a year when I got everything back into shape. As a rule, I eat a lot of healthy foods, which I cook myself, but I eat a lot, emphasis on
a lot which was fine when I'd work out 8-10 hours a week. The thing is, you get used to a certain amount of food and the body wants it, exercise or no. In one way, that year when I got fit again may have been the worst, because I proved to myself that I could more or less will myself back into shape in a few months. Not so good at willing myself to stay in shape though. After that it turned into a game of, "Well ten pounds, I can drop that in a week..." which turns into, "Meh, I'll skip leg day, or warm ups, or super sets..." and soon the weights are gathering dust...
And in the last few years, kids... which meant that for a couple of years we cooked/ate whatever would keep them quiet. And, then 18 months of work-from-home... And, over this time, I'm ten years older, and then... COVID. So, yeah, things fell well back before COVID, but it's an exclamation on a bad slide downward.
I've never felt a lack of strength like now. Honestly, I have to remake my body a little differently. I can't carry an extra 50-60 lbs anymore, which I did easily ten years ago. I didn't even really look worse for it. Not to humblebrag, but people would never guess my weight then. I certainly wasn't shredded, no one was confusing me with a model/gym rat, I had padding, but lifting makes you pretty dense/powerful and hides a lot. I actually don't think that 50-60lbs is enough loss anymore. In 10 or 20 years my body won't carry even that. I should probably drop close to 100lbs
which would make me about the same weight I was in highschool!