While studying theology in grad school I heard a great definition of vocation: where the world's greatest needs meet your greatest gifts. Since grad school, I have often used that definition. It's a great starting point when considering a career or a career change.
Yesterday, my husband found this Venn diagram (haven't yet found the original source):
This diagram makes my simple definition look, well, lame. Frankly, I'm looking for a job that would be blissful. However, when the economy is slower than molasses in January, you might not be able to get your dream job. As the diagram shows, there are many levels of happiness in a career path. And, you don't have to study theology to find bliss - thank goodness! Theology and ministry is my path and biology and technology is the path for my husband. It would be agony if I'd have to study biology.
The path to bliss, on a career level at least, is different for everyone. Yet, it is the same Spirit that inspires us all to follow our bliss.