I would go back and do EVERYTHING differently. Probably starting from a young kid, single digit in age. I've pretty much thrown my life away, and I regret almost everything I've ever done, or not done. My life would probably be completely different if I could change it...not a mother, not married, never met DH, have an education, never start smoking. Seriously, I could go on forever.
Too bad life has no rewind option. Would you change anything?