Who am I? in Life's ramblings

I got caught out with this question a while ago… I didn’t know how to answer. I fumbled and felt stupid. I’m seen as this reasonably successful entrepreneur & businessman, but such a simple question stumped me.
I guess I am a product of what happened to me during my life. I’ve had a reasonably good life though - so why am I unhappy? Is this just a short term glitch? Will I find happiness again?