Mortification is about indwelling sin, not the physical body.

Christianity is almost the only one of the great religions which thoroughly approves of the body—which believes that matter is good, that God himself once took on a human body, that some kind of body is going to be given us even in Heaven and is going to be an essential part of our happiness, our beauty, and our energy. – C.S. Lewis

Mortification targets the heart, not just behavior.

Mortification leads to progressive holiness, not sinlessness.

“The goal of mortification is a life of genuine holiness that results from the gradual weakening of sin’s influence in our hearts and lives.” – Brian G. Hedges

Mortification is for believers, not unbelievers.

Jesus invites non-Christians to come to him, and offers them rest for their souls. But to us, we who claim to love and follow him, Jesus demands drastic measures in dealing with our sin. – Brian G. Hedges.

Memorize Romans 8:13
"For if you live according to the flesh, you will die; but if by the Spirit you put to death the misdeeds of the body, you will live."

Surrender your life to Jesus.