Gary North delivered a wonderful lecture last month during Mises University 2009 (the same day I gave my own speech), “Calling and Career as an Austrian School Scholar” (a shorter version of this was in the LRC podcast 127. Gary North: Making a Difference, Making a Living, which is also excellent). North talks calling and occupation. Calling is “the most important thing you can do with your life in which you are most difficult to replace.” Occupation is “how you put food on the table.” Occasionally they are the same, but often not; but there is no reason not to arrange your life so as to have both. He talks about how to combine them or at least have both in your life, and centers his talk around some examples, notably Burt Blumert and William Volker.
Also see Paul Graham’s “What You’ll Wish You’d Known (“I wrote this talk for a high school. I never actually gave it, because the school authorities vetoed the plan to invite me.”)