The race is won based on our relationship with God by faith (Heb 12:1-3, Jam 1:2). Faith works in us (1Th 2:13). Endurance is paramount in Christian life (Jam 5:7-11, Act 14:22). James directs our attention to Job's endurance. Outline of James can be found in Jam 1:19. Believers admonitions similar to Heb 1(Jam 1:21-22).
Heb 12:1-3 says we're in the arena God has predetermined for us. We have our own personal race. We start the race when we become Christians. The race will be finished. We race against ourselves (Spirit vs flesh). The end is evaluated by Jesus Christ.