If you're lame now, you won't go. If you keep being lame, well, you'll never go.

I do have occasional regrets about stuff i didn't do in my youth, not so much in a 'misspent youth' sort of way but more in the 'i had all that energy then, where will i find the energy now, let alone in the future?' vein. My experience shows that it's not a matter of energy, but motivation. I have that now, and i'm sure i'll have it later.