Call it the 20-20 rule: As little as 20 minutes of low-intensity aerobic activity such as walking can give you a 20 percent surge in energy.

Many people assume that they’ll get tired from exercise, but the opposite actually happens.

It’s unknown as to what the biological mechanism is, but indirect evidence suggests that brain chemicals such as dopamine and serotonin are altered and cause the improved energy.

Besides, that quick recharge just burned about 75 calories.