Take a photo of the room. Our brain is generally lazy and only sees what's new or novel, so we become blind to long-term piles of clutter. Whe you see your room on a photo, you'll see all the stuff much better than you normally do! It can be frightening, really
I'm a fan of Flylady- whose mission it is to encourage everyone to declutter. She says "you can't organize clutter"- and how true! I can't follow the Flylady plan to the letter, but reading the Flylady website and using some of her techniques has helped me get so much more organized and get over the physchological hurdles of cleaning!