Spiritual gifts are different than natural talents. I have found that sometimes when you begin to use a natural talent like teaching or your natural compassion for praying for the sick, there is an added layer "anointing by the Holy Spirit", which takes it to another level. If in teaching, you find words of wisdom and understanding just ready to be said that you haven't thought about before. In praying for the sick, all of a sudden you will KNOW that the Lord is ministering healing and your prayer will join with what he is doing.
Most spiritual gifts begin with whatever your passion is for. If you have a strong feeling for the sick, that will be where God uses you. Or a strong love for the Word, you are probably called to teach it.
Remember that you aren't given the gifts for yourself. The gift of teaching is for the one who needs the teaching, the gift of healing is for the person who is sick, the gift of prophecy is for the one who needs to be comforted/instructed/exhorted. You only hold the gift for the one who needs it.