This is how People who drinks coffee tend to be smart.

When caffeine enters your blood stream, it acts like fuel. It also increases the adrenaline level in your body to significantly enhance your physical performance. 

Some suggest that you have a cup of coffee roughly an hour before you hit the gym or engage in a physically engaging exercise.
Also coffee keeps your spirits high,  reduce risks of suicide and reduce risk of brain diseases like  Alzheimer’s and Parkinson’s.