.. willpower and in changing your own behaviour to accomplish anything you like.
First of all, just change the way your mind approaches stuff, if your brain tells you "This aint fun at all" then you need to decide something like; "It might not be fun, but I will do this so I can feel good afterwards".

You see, everything we do in life we do to reach a goal.
If you are hungry - you eat.
If you are tired - You will sleep etc etc.

If you want a car.. You want to work so you can afford one.
To work - you need to fix everything else around you you do a good job, right?

Im too fat.. No you aint.. and if you truly belvie youare, then do something about it.
Every goal we set up in life, almost atleast, is never out of reach, it might just take a little longer to get there..

Take a minute - Think about it!