I would also highly recommend a book by Cal Newport called "Be So Good They Can`t Refuse You" that goes into great meaningful depth and detail on this topic with excellent real life case studies and application of what is best to do. The author himself wrote it for his own discovery and to show how misleading "following your passion" can be. Excellent book. I just finished reading it twice and have found it the best resource for answers I have come across as I too share this concern. Good luck.