To me, success is happiness. I want to reach a stage in my life where I am able to wake up everyday and know that I am happy, but not just meeeeeh happy, genuine, deep down happiness! I want to know for myself, that if I am ever put to test for anything in life that takes me off my path, that I am still able to reach a level of happiness... Then I will consider myself successful :)
And that's an excellent definition of success, from where I am sitting! And you're quite right... it has to be authentic and deep.