Motivation, such an interesting word

Where does motivation come from?
Why am I motivated about some issues but not others?
Why can I not keep motivated to write my essay?

I have this final exam essay to write and I love the topic, I enjoy reading my data but I can not start writing.
I can not put my thoughts into words. I would rather spend my time watching TV, facebooking or reading something completely different.

I dont know what's wrong.

But I'm getting more and more settled in here in Copenhagen. I am starting to grow to this environment, learning my ways around and feeling comfortable at my home - love it!
The only thing missing is my motivation.
Both for my essay and also getting out in evening to meet friends and potentially start excercising.

So that's why I'm wondering about this word "motivation" and where it comes from. Why am I motivated about some things and not other?
What motivates me?
Interests = Motivation?

I love these questions as I think about the answers as I post them here.
Now I just have to really think, and hope to find my motivation and delegate it into my essay.
Let's hope :)
-with love-