"And David spake unto the LORD the words of this song in the day that the LORD had delivered him out of the hand of all his enemies, and out of the hand of Saul." 2 Samuel 22:1
You can read the song which is 2 Samuel 2-51
The Lord speaks to us and we speak to the Lord. But more than that, I think this verse shows that there are many ways you can give back to the Lord. Singing was David's talent, but what about art or carpentry and through being a physician or a nurse or a computer programmer or a film maker? Giving your talent to the Lord is a great way to give back and to come into a closer relationship with God. Doing something you do anyway, but doing it with excellence and in direct acknowledgement of what God has done for you.
You can't have been a Christian very long and worked at a trade and not seen the Lord at work on your behalf. If you follow your career carefully and look back, you can easily see the hand of the Lord at every turn. It's not that you always made the right decision or that you always enjoyed a positive outcome, but if you look, you can see the hand of God, invested in you, guiding you and sometimes carrying you. This being said, look unto heaven and give of yourself to God. Find a way to do something for the Lord with your talent. Think hard and find a way. Whatever you do will bless the Lord and benefit others.