Perhaps need to look at it 2 ways... and with different response.
1. If you could go back to the time when you were 21 with what you know now.
2. You could become 21 NOW and have the common sense to accept Grandpa's Wisdom.
(When I was 21, I was eagerly looking forward to the future and all of the good things it was supposed to hold for me. NOW... I'm just hoping to get to live out my life before the government jack-booted thugs come haul me out into the street and put a bullet behind my ear just because they want to take my house.) This is no longer my Grandpa's America.
:>(