First, you must want something then:
1) Think about what you want. Explore the depths of why you want it and how you want it and when.
2) Make sure it is something you have control over - i.e., not controlling someone else's behavior but changing your own.
3) Be determined! Set goals, think about it every day, talk to others about it, study the subject.
4) Be flexible. After you have explored your goal, you may find that the goal was only a preliminary step toward something even greater.
5) Be grateful that you know you want something. Too many people go through life not knowing what they want at all. You are fortunate.
The best of luck to you!