One study found that your body's ability to perform peaks in the afternoon. Your body temperature increases throughout the day, optimizing your muscle function and strength, enzyme activity, and endurance for performance. Between 2 p.m. and 6 p.m., your body temperature is at its highest.

Several research studies suggest that in terms of performing a consistent workout routine, people who exercise in the morning tend to do better. According to a study published in the Journal of Physiology, working out early in the morning, as early as 7 AM, may shift the body clock earlier.