It wasn't a book or article, only finding someone I used to go to school with on Facebook that prompted me to think about my own perception of success. The person in question, who initially didn't perform well in their A Levels, is now a Physics student with some of the world's best universities under his belt.
It occurred to me that while his achievments are impressive, they're not mine either, nor do I hope to ever come close to achieving them. On the face of it, this isn't a particularly difficult idea to get one's head around. Let's hear this one more time.
Other people's achievments are their own.
On the flip side, if my goal was to study Physics at the best intitutions in the world, what then? Would I have achieved 'success' if I reached my goal? What would I aspire to do after? The reality is, nobody knows. I'd have to get there to find out and probaby take multiple unexpected turns along the way.
As I start to think about where I sit on my own path to success, I realise there's really no end. As a developer I continue to grow, but ultimately I decide when I've accomplished something with enough substance to have acquired it.