Despite the objections of idealists, in this world of reality:

It is who you are.
If not, it is what you have.
And if not, it is what you can do.

Because, the opposite is:

It is who you are not.
It is what you do not have.
It is what you cannot do.

And those last three are the very foundations of fantasy.

They are also the factors in the premise of every superhero comic strip and movie.