This is about the focused athlete and his attitude to the race set before him. You run the Christian race as if you alone can win.
So who are we running against? We are running against all those influences which are liable to slow us down, or take our minds off the finishing line. Why is a race a suitable metaphor? Because the Christian is like an athlete, straining to keep his mind on the goal. He strains forward and constantly pushes himself to the limit. There is a constant temptation to ease off, to rest on our laurels, to give some leeway to the flesh. Our battle with sin requires the same degree of dedication and commitment as an athlete, who does not listen to the complaints of his body, but sets his goal above any discomforts he or she may feel. It requires the same self-control and self-discipline. Sin is trying to beat us; temptation is trying to disqualify us. The fact that no believer can lose their salvation does not make this contest any less real. Satan has not abandoned his cynical belief that all Christians are serving Christ only for selfish reasons, and he is still trying to prove it.