Motivation is the reason that someone does something.
In the interest of people hitting their life goals, motivation is a crucial thing to understand so that a person's time is well spent.
Motivation empowers people to achieve tasks that others often see as impossible. An example might be, what motivated the first person to reach the summit of Mount Everest?
A key understanding to have is the difference between intrinsic motivation & extrinsic motivation.
You need to know the difference between both if you want to influence human behavior. Whether that be your own or someone else's.
Translating motivation into hard work results in an increase in one's self-esteem and helps people to reach any long term goal they may set for themselves.
In the long run, one of the best ways to improve human motivation is to set a big goal and back it up with external rewards. It should also have a support group in the form of an accountability partner.
Research in the field of positive psychology shows that self-motivation is supported by setting large goals with intrinsic and extrinsic rewards. This is, in essence, the self-determination theory.