Have you ever noticed that, when racing, runners tend to wear the lightest outfit or the least amount of clothing possible? From the weight of their shoes to the amount of hair on their heads. Why is this so important to them? The answer is easy: because the less you have weighing you down, the faster you will be and the more endurance you will have.
The same principle applies to the Christian life. Several times in his letters, Paul relates our lives as Christians to running a race. When running this race as Christians, God wants us to run with perseverance because He has so much set out for us to do. But, when we allow sin to cling to us, it slows us down.