You must take the first step towards it. Motivation won't come looking for you. It's pretty obvious that good is an easier motivator than bad. So search for good in everything and everyone. Don't brush it aside, but experience it and live each moment as it comes.
Motivation is a day to day thing.
Each day, as each situation arises, stand by your choice. If you let your emotions control your motivation, you will run into trouble. Times will arise when you don't feel like doing so and so, and you won't. You must persevere. This is where discipline comes in.