As with most addictions, people are very good at ignoring how bad the disadvantages of the habit feel. Sometimes just acknowledging how much your clutter trips you up is enough to give you a push in the right direction, but you're right, if it's got this bad, it's going to feel worse before it feels better!

I find that my desk stays tidy all day and I focus much better on whatever I'm working on if I stick to doing one thing at a time, and put all the papers etc relating to that one thing away as I finish it. Really helps me to feel I'm powering through work, and keeps my energy levels and work satisfaction levels up too! But, if you're going to do this, having a good system to make sure you check in with everything you're supposed to be taking care of without the visual reminder of it being on your desk (nagging at you!) is essential...