In terms of spiritual growth - realisation of the soul - success is not so much a measurement of size or number, although that can be a reflection; neither is fulfillment about reaching some kind of goal or destination. What I've found for me, is that there's what's real for me; what defines, and best reflects, who I feel I am. This is actually the hardest thing - to know the fineries of yourself in all situations. It's a case of being able to define one's boundaries accurately, by being prepared to explore all the grey areas of uncertainty. As you refine you, one's life streamlines and focuses. It feels increasingly authentic. For me, this is true success, true self-actualisation, and there's nothing like it. Things keep clicking into place. It feels like magic.