You need to have a clear vision of what you're ultimately trying to do. Then, and this part is crucial, imagine that you've actually achieved that goal, and that you're telling a friend how you got to where you are.
What actions did you take? What was the path - the steps - that got you there?
What behaviours did you use? What was unlikely to have helped?
Come back to now. Do you think there's any benefit in putting off a certain task? Nope. So, what's the logical next step to take that takes you nearer to your goal? If you still feel stuck by that step, it's probably because it's too big, in which case break it down, or because your fear something about it. Decide whether the fear is real, and if so, whether you want to face it and do the task, or not face it and don't do the task.
In 5 years time - and it'll creep up on you - do you want to be saying, "Damn, I really wasted the last 5 years doing f*&k all"?
It helps if you write down the steps. How are you at following written instructions to put a piece of furniture together? Write your own instructions. Then do them.
You are not your brain. It's a very (very) powerful tool that you can use to help you get to where you want to go. Think of it like a horse pulling a cart. But, like a poorly-trained horse, it'll go where it wants to if it's not led properly. Usually, that's in the direction of the nearest and quickest source of pleasure - carrots, polo mints, grass, etc. in the case of the horse.
Grab the reigns of your own horse and guide it to where you want to go. Once it has instructions from its owner, it'll follow them with joy. But, don't overload it with too much at once: write stuff down to put into it, let it do a bit of thinking, act on it, and then write down the answer it comes out with. Repeat.
You use your thoughts to guide your brain. Otherwise it'll think up it's own and it'll keep you where you are. Here's how: think of a warm summer's day, trees swaying in the breeze, ice cream in hand. Now think of a busy motorway with rain pelting down, and the dreariness of the whole scene. See - you can control your thoughts. Decide to choose the most helpful thoughts. Simply observe any counterproductive thoughts that your brain comes up with, thank your brain for them, and then choose to think something more helpful to the task at hand.
Finally - think up as many negative consequences of not reaching your goal. Now, get as far away from them as possible by taking ACTION. Don't leave it until they come to bite you (it's painful, believe me).
Action can be exhilarating. I love the zingy feeling of powering through tasks. It's much preferred to the boring, lazy feeling when I'm sitting in front of the TV when there's work to be done.
Also - most things in life are very simple. Don't make them hard, because then you won't want to do them. Ask yourself: "What's the simplest way to do this?" Do it, and then be done with it. It's a great feeling.
But you need that clear vision of what you want, and a clear vision of the danger if you don't do it.
You just have to decide.
I wish I'd done the above 5 years ago.
You may find the following books helpful:
'Focus', by Jurgen Wolff
'Managing Thought', by Mary J. Lore
Teach Yourself - Be A Great Entrepreneur
And any biographies of famous entrepreneurs.
Find some motivational books or audio books and read / listen to them for 5 mins every morning.