I realized this on Friday: After 8+ years of programming I still get a thrill when something complicated I am working on, or something new I am trying actually works. I get a kick out of seeing software that I wrote working. That is how I know I am in the right industry.
When things don't go right, I get frustrated, and really want to solve the issue. Again, another indication that I am in the right job.
On the bad days I may not like my job, but on the whole I still like programming a lot.