People who are 30+, what career moves do you regret in your 20s and/or what choices are you happy you made?

I'm not 30+ yet but getting close and there's a thing I already have so

I've stayed at one place for a bit too long, wasted time not learning new skills and now that I'm looking for a new job, my resume looks a bit sad and I'm not sure the company-specific PM skills I gained at one place are going to be useful enough in a different one