I was going to reply yesterday but...no, really, I mainly wanted to say that if you are young, try to get rid of this habit, as it only causes you harm in the long run. This is an issue I am well familiar with and wish I had nipped it in the bud in college. Getting into the best working habits early spares you so much pain in the future, especially if you plan to go to grad school or end up in work that you have to do on your own.
Sorry for going on at length, but I'm procrastinating.
Retrain yourself to work in a more timely fashion as soon as possible.
I used to think that I worked the best under pressure, producing my best work. But, you know, how would I know, since I never see what I could produce when I'm not under pressure. Basically, what I'm saying is...perhaps your best work comes from a different way of working. Try to figure out how you work best and try to re-create those conditions in a more effective manner.
One thing I found that did help was to work away from the computer (e.g., sometimes I write in longhand rather than on the computer). If you must work on the computer, have one that isn't attached to the Internet. (The Internet is the biggest time killer ever.)
Another method that could work is to break down the project into portions/sections and work on it section by section. If you start early in the day, later in the day you can celebrate your success (within reason, an Adje or two could help). For long projects, I try to apportion how much work I need to do each day to finish by the deadline. If I do more work one day, fine, but if I do less, I reapportion the remaining work. It does help. As for the difficulty of sitting at the desk to do the work (or wherever), that can be more of a struggle.
I always thought that I worked best in intense, solely focused periods (that is, obsessively). I do work well that way, but that doesn't always fit the circumstances. So, now, I try to achieve that sole focus for specific projects by working in headphones, listening to strong music that blocks out overwhelming superego negativity. This helps me work more obsessively; the headphones shut out the world (symbolically) and at the same time help me focus solely on what is in front of me. Before I never worked with music on, preferring silence, but this method allows me to block out the world but still be in the world (I know I’m still in the world and missing nothing—I’m just choosing to block it out). One of my issues: I might miss something going on out there!
I think you have to figure out how you work best and try to re-create or refashion these best conditions so that your work can be done more efficiently. For me, I missed being involved in the world, so I resolved it by blocking out the world with music via headphones, which allowed me to know the world was out there, but I’m in my own little cocoon. I know I’m procrastinating when I avoid listening to music.