There are people, many in fact, who despite knowing how important exercise is to their well-being, will struggle to remain focused on their health and fitness for long periods of time. This is due largely to how the human brain organizes and perceives the importance of goals and rewards based on time-frames.
The human brain, like the rest of the body, functions to protect and keep us safe. Objects or events (like a waist size or a race) that are far away are not as significant to us as objects that are near to us and because these events are in the future, they don’t present an immediate risk and therefore do not demand our attention.
A similar phenomenon occurs with rewards and time – a reward that we will receive sooner, is perceived as greater than one that will happen further on down the track. This makes even more sense when the rewards are identical, because not having to wait for something is more satisfying than having to wait for the exact same thing.