If I'm So Smart, Why Do I Have Debt?

I consider myself to be a fairly intelligent person, so why do I have debt? Here are a few reasons why I have debt that are not unique to other 20-somethings out there:

Student Loans. My parents did not have the money to pay for my college education out-of-pocket (not a unique situation these days), so I took out student loans to finance my college education. I was also a decent high school student, but did not receive much in scholarship money. But I did not want this to prevent me from attending college. I know this debt is well worth the expense, but it IS still debt that I will be paying for at least the next few years—unless I get some crazy, unexpected windfall sometime soon. For this reason, I am trying to figure out how to NOT accumulate more student loan debt in reaching my short term goal (during the next 5 years) of obtaining a graduate degree.

Supporting Yourself Isn't Always Cheap. I got my first job out of college the summer after I graduated and relocated back to the city I attended college in (Washington, DC). Because my family resides in another city, I didn't have the option of living at home for a while to save up money. For the first several months of my first job, I had roommates; I have lived on my own for the past 10 months. I love my independence and enjoy the feeling of knowing that I received only a moderate amount of help from my family in learning how to support myself.
But because I didn't have the fall back of living at home for a while (which would have been a pretty good decision in hindsight), combined with the fact that I live in a city where housing isn't cheap, a big chunk of my take-home pay goes to rent, utilities and other living expenses.

Former Spendthrift. I wasn't always committed to finding ways to live in style on a small budget. So as a result of my spending habits in the past, I have credit card debt… If I stay on track, I can pay all of my credit cards off by March 2009, but this will take discipline. I am fully committed to paying off my credit cards and not ever have credit card debt again once they are paid off. I think credit cards are great and would encourage people to use them, ONLY IF they can pay balances in full when the bill is due.

So, I pose the question to you, why do you have debt and what is your plan to get of it?