Firstly I think it is the direction you choose.  Everyone has his/her gift which is given by nature. If you are lucky enough to find the field you are good at it is very possible you will succeed in your career.  This very likely happens to artists. Not everyone can be an artist.  Artists need creative spirit though they also should learn some technical knowledge. 
The second factor would be confidence. You have to trust yourself: believe in your capacity to get through whatever hardship.  Miracle is everywhere. Miracle is created by people.  You can make miracle too.
The following factor should be diligence and persistence. Why the two words are mentioned together? It is because I think the two are inseparate.  People have one virtue of them usually have the other one.  Even though you have the gift in some field you can't realize your dream if you don't equip yourself with the wings of diligence and persistence.