Hebrews 12:1

Therefore, since we are surrounded by so great a cloud of witnesses (who by faith have testified to the truth of God’s absolute faithfulness), stripping off every unnecessary weight and the sin which so easily and cleverly entangles us, let us run with endurance and active persistence the race that is set before us. 

Sin halts any forward faith movement and causes us to take a side road to nowhere. We must continually guard our thoughts, making sure we use the filter of the word to keep us on track. When we are persistent with ourselves in following the word, we will see God working on our behalf and guiding us through the race set before us.