S.T.
Nicole,
You've received really great advice so far. My recommendation to you after taking a 3 month procrastination cure course to learn to deal with this type of thing is this...
Do the tiniest thing possible and reward yourself.
This may vary depending on you and your personality, but if I were in your situation, these are the steps I would take:
Day 1: Go to store and buy those cardboard file boxes. Open them up, put them by the file cabinet. Tell myself: "Great job getting prepared to declutter!"
Day 2: Take out part of the files in the cabinet and place them in the box (or all if it felt OK). Tell myself: "I'm the kind of person who declutters my home."
Day 3: Maybe continue from yesterday (fill the box and put in storage), maybe move on to next step: Filing ONE piece of paper from on top of the cabinet. If you file just ONE piece of paper each day, in NO TIME it will be gone.
Now, I don't know about you, but sometimes when I look at a stack of papers like that, I feel like "there's no way I have time to do that," so I just leave it. IF I tell myself, I only have to do 1 piece of paper, I am much more likely to do at least 1 and very often way more than 1.
Try to make it fun and silly if there is any way to do that. Just ask yourself: "What is one, tiny, insignificant step I can take to clear these papers?" And let the answer come to you...maybe at 2am or in the shower, you'll have an epiphany and think "oh yeah! That's it!"
Hope this helps in addition to all the other great advice!