If you see a little child you can see the spark in their eyes. As we grow we keep loosing that spark. Life gets harder and keeps sucking the motivation out of us. I think motivation is the most precious thing in life and we loose it so easily without even being fully aware of it. As I grew up the most difficult thing I've faced is to keep myself motivated. The dreams we dream don't just come true. Our reality is totally different from our dreams.
Motivating ones self is actually simple. It's a matter of setting goals. Short term goals that lead to midterm goals all the way to long term goals. These goals and how we achieve them is a good place to look for motivation. Actually the key to all these is to set and achieve compounding short term goals. Keep them achievable, time bound and simple. Keep in mind that short term goals are easily achieved, achieve enough short term goals to compound and become midterm goals that in turn become long term goals.