It was a long time ago, but I actually remember getting up in the morning and just starting my day. If I'd done something really strenuous the day before, like help someone move some furniture or something, I might feel a bit sore, but that's to be expected. Stretch a little more, get moving.
Somewhere along the way, I noticed I'd get up in the morning, and I'm moving slower, and there's random soreness or at least tiredness in my legs or arms (or both), and I didn't help anyone move yesterday, I didn't foolishly try to play volleyball for the first time in years or anything like that, I just feel kinda tired and sore. I then I realize that it's been that way for a while. At some point, I became old. I'm not tired and sore from doing stuff, I'm just tired and sore all the time anyway, because my body is now old and tired. What the fuck happened to me?