In their book on willpower, John Tierney and Roy Baumeister suggest that one way to overcome procrastination is to commit to doing nothing if you're not doing the thing you're supposed to be doing. Nothing, as in no reading, no watching TV, no listening to the radio, certainly no surfing the web. Just nothing.
Their premise is that you will soon get so bored you'll decide it would be better to do the thing you were avoiding.
Actually, sometimes displacement is quite useful; I think it was Robert Benchley who wrote that he got the most things done when he was supposed to be doing something else.
However, if you're doing too much of that, you could try their 'do nothing' approach. I'm not convinced it would work for me. I'd still be thinking and that might be enough, although I'm sure I'd find it frustrating not to be allowed to jot down ideas as they came up.
If that might apply to you, too, I've come up with an alternative:
Think of two other things that need doing that you would find even less appealing than the thing you're supposed to be doing. For instance, maybe cleaning the toilet or sorting out your tax receipts.
Then commit to doing one of those three things. You can allow yourself to switch as soon as one got too unpleasant; maybe you'd get 1/3 of all of them done the first day, the second third the next day, and finish them all the third day.
As with every other challenge, the key is to keep trying things until you find the one that works.
(For lots of useful, practical tips on how to make better use of your time, get my book, "Focus: use the power of targeted thinking to get more done." You won't find thes same advice in it that is featured in most time management books, these are right-brain approaches for creative people. You can get it now at Amazon or your other favorite book seller.)