I'm not usually one for religious self-help books. I find that merging the two subjects usually makes for an inferior treatment of each. While I'm trying to be a thoroughly Catholic nut case, I prefer my Catholicism to be foundational, informing all of my decisions*, but to leave the mechanics of my decisions to other approaches. Sifting through our library looking for material on this topic, I came across Max Lucado's Cure for the Common Life.
Max is a Christian writer and this is a very Christian book. His points are illustrated through the use of stories and excerpts from the Bible. That's all very well and good for Max, but for me, I felt the book wasted a lot of space on Biblical teaching that added very little to finding your calling. For me, a Rosary and Adoration Chapel would accomplish more than all the Bible quotes Max could find.
In spite of this, Max had two diamonds in his rough that changed the way I see my life. The first was to look back on your life to find episodes that had brought pleasure and fulfillment. In a perusal of my checkered past, I quickly saw that I was most energized when I was leading some kind of crusade, whether that was at work, with the family or in my hobbies. When I was trying to do something that was particularly difficult and perhaps never done before, I found practically limitless reservoirs of enthusiasm and determination.
Ironically, the second insight came from one of Max's Bible stories. He used the Parable of the Talents to say that God doesn't want you to think small.
While the rest of the book was skimmable at best, the first of those two nuggets was life-changing and the second reinforced it. When I try to sell people on reading self-help books, I frequently get push back - "Well, that may work for you, but it doesn't work for me. I find too much wrong in the author's work." That attitude is self-defeating and can cause you to miss marvelous nuggets of wisdom. No book has universal, total applicability, but most of them have something unique you can pluck out and use to improve your life.
* - Informing isn't the same as doing. See also: sin.