Aviation photography;
For me, it comes from my aviaton love. Once you fall in this love and  if you add photography love in it, it evaluates to an other form of love.
Your eyes automaticly locks on every flying vehicle around you and you have your finger on you camera's trigger.
You shoot'em in the airshows, you shoot'em in the military execises , you shoot'em in the airports...
And you will never surrender... ;)