This is a subjective question!
And a good one.
It depends of course on what you consider to be successful.
Whatever you wish to achieve though needs a few key ingredients.
The one that has stood me in good stead is:
Persistence.
Not trying the same thing, but never ceasing to keep trying to achieve whatever goal it is that I wish to achieve.
If you love what you do, you will persist, so finding out what you truly love to do is a key as well.
If you take the other two and fuel them both with passion, well, you will truly be on fire and succeed for sure.
E-GO 2018