Ahh, yes – It took me many attempts to get through my thick head that aerobic fitness doesn’t mean you can jump from one exercise to another without consequence.
I avoid running, not because I don’t enjoy it, or think it’s bad for me, but because I know if I go out for a straightforward run, say 10k (45ish mins), I will be ruined for at least three days, and that’s lost time I could be doing other things.
If you’re interested in exercise generally, I can recommend reading The First 20 Minutes. Lots of interesting bits of info based on up to date research, a lot of it contrary to popular/common exercise belief.
I only mention it here, on reading comments above re ‘proper running shoes’, importance of stretching in exercise etc. You can take what you want from it, but I found it really interesting…