I once heard that if you want to identify your life's ambition, just write out what you'd want written on your tombstone. That means it has to be brief but tell a life's worth of meaning.
For example, mine was (mind you, I was 19 when I did this) here lies Roman Roberts: a man that served his community and had a loving family and many friends.
Early in my life, I had an intense and selfish desire to achieve my goals (greed) so that I could live the life I wanted, but I never cheated anyone to reach that goal. I worked 50 hours a week at a factory, went to school at night, and studied all weekend. I would study until three or four in the morning, work a full day, and then head to school for exams. I would make flashcards and study in the bathroom or during any break I could get. And as I achieved each goal, through hard work and sacrifice, it only built my confidence and pushed me to work harder to achieve even more.
I hope that in your journey you too will not be afraid to work hard and sacrifice not only sleep but money, time, or even a family, if it means being able to achieve your ultimate goal. No one else can decide what's right for you to do with your life. But I hope you will always keep this in mind and do it without sacrificing what's right.