I used to have fairly good money management skills. After paying off student loans within two years of getting out of school, my credit was top-notch.
Then I got some high-limit credit cards when I was about 22...like everyone who gets their first credit card in the mail, you swear you'll "only use it for emergencies" or "only buy one thing with it, then pay it off right away". Pretty soon, like almost everyone I know, I was living off of those little pieces of plastic. I simply wasn't living in my means.
In 2001, I enlisted in the Navy, which really made things hard.