My job is very fulfilling. I am doing what I love, what I am educated and trained to do, and getting paid to do it! I help my patients every day, and I learn something new from every one of them.
I think having fulfilling work is necessary for one's sanity and to feel one is contributing to the World at large. I understand that in this economy, it may not always be possible to do exactly what you want for your paid job.
But, when one's job isn't
as fulfilling as one wants, doing volunteer work in a field one finds fulfilling is an amazing thing! I volunteered as a breastfeeding lay consultant for several years before I got my MS Certification. It taught me a lot and also gave me a career, and I was helping people in the field I enjoyed while I was learning.
I can't think of much that is more fulfilling than volunteering in a field one feels strongly about.