A persons answer depends on what they consider success.
IMO knowing what you want to do for a living early in life and doing what it takes to achieve that job. Having knowledge on how to invest your funds. Surrounding yourself with positive and like minded people. Knowing yourself well enough to know whether marriage is right for you and, finding the right mate.
Finding what talents you have and acting on them even if its just for fun.
Be true to yourself. This is #1.
BE THE PERSON YOUR DOG THINKS YOU ARE! (unknown)