What can be done to make my brain work faster and how to keep my body fit?

It all boils down to: Clean diet, adequate rest, activity (exercise) and stress minimization. Improvement in any or all of these will improve brain function and overall fitness. Regular vigorous activity improves well being which improves mental acuity. Following any holistic exercise regimen will do the trick. Stable sleep patterns and meditation will boost awareness & overall brain function.