Unintentional Visualization
Everyone has dreams about races where suddenly their legs are peanut butter, or the track has turned into Möbius strip, or a mountain has appeared in the middle of nowhere. These allow your brain to work through worst case scenarios and build endurance, so that when the moment comes your fearful instincts don't take over. Practice visualizing races, visualize winning, but visualize losing, too. Temper your mindset so that you don't dump all your adrenaline at the crack of the gun.