I love the challenge of making things work, especially if others have tried and failed. I like that every day is different. I get to set my own schedule, I can work from home (sometimes), I have great work/life balance, and I make more money than any other job I've had.
+1 on this - especially the part of making something run that others have not been able to.
And when the other is supposedly better educated or more qualified than I am, I grin bigger.