Mine just stemmed from a long-time 'need' to understand how things work. As a young kid, I always liked debugging code from other people, and had a knack for finding coding flaws and mistypes. The challenge intrigued me, in trying to better someone else's stuff, or even just fix their mistakes, so I could use the programs. Later, when I graduated school, I began working for a couple of retail shops, and saw how they misconfigured things, as well as leaving mgmt passwords lying around, etc. I worked hard, and engaged the right people, to show them the value of a more secure environment. It just continued to grow from there, to where now, I work for a large software company, and have opportunities to show value in both pentesting our own products, as well as showing my customers (and sometimes co-workers) where they're lacking in their overall security postures, in general.
Additionally, I do a lot of security training and speaking on the side, and use ethical hacking as a base point, to show others the value of proactive security analysis, rather than reactive.
~ hayabusa ~
"All men can see these tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved." - Sun Tzu, 'The Art of War'
OSCE, OSCP , GPEN, C|EH