Things tend to pick up speed as they go down a hill. Put a car in neutral and send it down a big hill and you might be able to get in front of it and hold it back if you do it right away, before it gains momentum. Wait until it goes a few yards and your chances become much slimmer. Let it get half way down the hill and you really don’t stand a chance, unless you are the Incredible Hulk.
Sin is much like this, I think. Catch it early, before it gets a chance to gain momentum, and your chances of avoiding it or reigning it in are much better than if you let it go too far. The Holy Spirit is, of course, helpful in this regard. So is prayer. Luther I think spoke often of how he would “go to his little Psalter” and start praying at the first sign of trouble. Too often we don’t take the warning signs seriously enough or we simply ignore them, and then it is too late. We’re like those people (like me) that like to wait around and see what a storm is going to do before taking shelter. And then it is upon us before we can do anything about it. Take shelter quickly, and you might be able to avoid being harmed by the storm.
There is a “point of no return” with sin and temptation, a point at which our minds have completely given in to the desires of our bodies, and we cannot hold back, much like a car going down a hill. Catch sin before it catches you!
We cannot keep sinful urges and temptations from assailing us, but we can change the way we react to them when they hit us. One way to reduce these is to cut off access to the things that entice us. If you have a weakness for chocolate, it’s not going to do you much good to have a counter full of chocolate bars.