I wish I didn't fear getting old back then. I felt old at 23, 25, and 28 and dreaded reaching my 30s. It made me feel it was too late to do things and made me settle for less way too many times.
I am in my early 30s now and no longer give a fuck. You are only as old as you think you are. I'm now trying to get started on things I wish I had done in my 20s, and hoping I reach my potential a decade from now.