I have seen people who have so much passion for music that they go to the studio to record a CD and then they give it out for free! Others have written world-class encyclopedia articles for free, and hosted them. Some young webmasters have built popular websites and blogs for the fun of it, with no intention of making back the money spent on those projects. All for the enjoyment they derive from these activities.
No doubt, there are some tasks/duties that you we love to do so much, to the extent that you're ready to keep on doing them even if there's nothing to gain. Mine is primarily that I just that I love to create clever strategies to solve problems that matter in my business, society, and so on. I like to analyse situations, understand and apply fundamental principles to solve them. What's what you really love to do?