I have never liked doing those exercises to discovery your gift. It always seemed too mechanical rather than being open to the Holy Spirit. Most of the time we do things based upon three criteria.
First, ability. What are you good at? It was never likely that my Spiritual gift would be music.
Second, affinity. What do you like to do? There are somethings that I like to do that I have no ability and there are somethings that I have ability but I don't like doing them.
Third, opportunity. When it comes to spiritual gifts this one is very important. Many times people discover their giftedness by doing something that just needed to be done.
I have never read the book but Kevin deYoung wrote a book about finding God's will called, Just do something. I think we can apply the same principle to discovering your spiritual gift. Just do something.