Stop exercising
Is exercise a good parallel for the Christian life? I ask because I'm often told that it is, and sometimes people point me to 1 Corinthians 9 where Paul uses the discipline of exercise as a model. So it is pretty hard to deny that it's there in the Bible: self-control, self-discipline, regularity, and application of effort that come with dragging yourself out of bed and into the running shoes, the gym, or whatever.
This is all good and true, but every time we meet an analogy, we should discipline ourselves, like a tennis player attending to his technique, to ask ourselves where the limits of the analogy lie. Paul knew this, and observed, with regard to the analogy of exercise, that “physical training is of some value” (1 Tim 4:8). Where does the value of the analogy run out of puff?
The most obvious limitation of the analogy of physical exercise is that, as useful as it is in building strength and health, it ends in death and decay. I've known some fit people over the years, and some of them are dead. The rest of them will be dead shortly, measuring their lives against the yardstick of eternity. So let's not get carried away with promoting the exercise analogy because, unless our Lord returns first, the fittest person in the world will end up in a permanent hole in the ground.
Theologically speaking, there is a more profound flaw: in spiritual terms, we begin dead. I have been to and presided at a number of funerals, but once the person is dead, it needs to be said that they are beyond the reach of exercise.
This brings us to the missing dimension: exercise depends on self and self-discipline. The Christian life only depends upon the grace of God. In the paradox of the Christian life, the person who admits that they are beyond help and that they can't do anything to save themselves is the one who is the strongest Christian of all. This strength comes not from themselves but from the free gift of Christ working through his Holy Spirit.
Now we know this to be true, but we need to exercise (if you'll pardon the expression) great care so that we do not allow ourselves to slip back into the idea that our personal and regular effort could ever improve a relationship with God that, through Christ, is already perfect. We work because he loves us, not because we want him to love us.