Yes! Everything I learned when I was young told me a) you have to be *very serious* about working out if you are going to do it and b) it's mostly about looking good.

Both of those turned out to be huge fallacies. I'm 40 now and not very serious about working out, but I do it reliably (on an irregular schedule) and I don't target specific muscles etc to try to make myself look a certain way. The result is that I am just plain healthier and feel great. That has many second order effects.

100% agree. The most important point is to make exercise enjoyable; the more it feels like a chore, the more you will not be getting out there doing it.

A corollary to that is to not overdo it, even if you have an enjoyable time while you do it. You shouldn't be too tired or sore when it's time for the next training session.

I wish I could agree with this more. Vigorously nodding will have to do.

Exactly. This is why I got into indoor boulder climbing. It's hella fun, and as long as it is I'll push myself without even trying.