Some excellent advice here from Mr Shallard. 

Like most psychology I read, the advice seems obvious – common sense – but only after you've read it. 

Slowly but surely, by deliberately doing nothing, you can nurture this desire to do things. Do so. Nourish the desire with your imagination, until you can barely tolerate the pain of not doing it.

Only when you can barely cope with the idea of spending another second sitting, doing nothing… should you get up and do things. Take the memory of your desire with you. Never forget it. Do what you want to do and watch yourself grow and evolve, even as your desires do.

Full article here: