Motivation is triggered by 3 things; need, value, and goal.

1. Need is pretty basic. I NEED food. So I become motivated to get some (either by walking to the fridge, or by going out to hunt and gather).
2. Value could be considered the scale that one measures the need. Lets say you decide to get fit. You may value being fit because; it gives you energy, it prolongs your life, it makes you happy.
3. Goals are the core to successful motivation. But for motivation to be successful, goals need to be specific, Difficult but attainable.