Interesting post from Seth Godin on reasons to work.
Similar in vain, however I think this comes down to
Recommend his blog, always thought provoking.
Reasons to work
1. For the money
2. To be challenged
3. For the pleasure/calling of doing the work
4. For the impact it makes on the world
5. For the reputation you build in the community
6. To solve interesting problems
7. To be part of a group and to experience the mission
8. To be appreciated