If I could do it all over again:
I would have had sex with every willing participant that I turned down from age 14-16. While oral was fun, sex would have been better!
I would have never joined the Army: It put me 3yrs behind in the salary & field I'm in now and I completely missed the tech boom in '99 and half of '00 where I could have had more wealth and actually been able to afford a home.
I would have never sold my '81 CJ8
I would have accepted that six figure job offer a year earlier