The Apostle Paul wants us to work with our hands in order to share with the needy (Ephesians 5:28). Notice that he could have said that we should work to support ourselves. But Paul says that we work to give to those in need. This is why caring for our body is also a Christian work. If the body is healthy and fit, we are able to work and save money that can be used to help those in need.

p. 80 - The Freedom of a Christian (1520)