Mortality....I love my life.I don't want it to end. I hope I can deal with getting old and dying when the time comes.
Worriness....I wished I didn't worry so much about my two boys. Almost to the point of sickening myself. Even when I know they're safe and sound I think of the worst.
On a lighter note.....I'd change the shortness of my schlong or my stature. Be 6'5" or have a 12" tallywacker.....can I change 4 things about me?