We tend to think of this body as our own, "it's mine and I will do with it whatever, whenever I choose." This is echoed by a society that says it OK for one or two consenting people to do (almost) whatever they want in the privacy of their own home, as long as it doesn't affect someone else.
If your father gave you an expensive car, sacrificing all of his savings, would you use it to store your junk in? No, you would value it and want to use it for its intended purpose.
I must disagree when someone says that "we are not free". Pick a verse of many, "you shall be free indeed" John 8:36; "Christ has made us free" (Gal 5:1)
It is a difficult concept, but we are like the freed slaves that choose to stay and serve their master.