The Apostle Paul stated that he was a "bond servant to the Lord".  What is a "bond servant"? 

He/She is one who has dedicated his/her life to the one he/she is serving, and doing it from his/her own free will.  As a bond servant, a person willfully bonds himself to another to be his servant from here on out.  This is what God wants us to do with our free wills ... give them to Him. 

This bond servant is not a slave.  A slave is a bond servant to somebody, but not of his/her own free will ... forced to be a slave.   Doing this doesn't take away our freedom ... we are still free ... but our main desire should be to please God.   We still have other desires that are OK, that aren't necessarily following God all the time, that have to be done in the natural to maintain things.  

Reverend Robert W. & Mary C. Butler