Physical activity and obesity are two of the most used health expressions over the last years ranging from the lay press to the highest ranked scientific journals. Both reach their readers, as everybody is either affected him/herself or knows a person which has to be treated - or has to cover an explosive scientific topic and search for solutions to solve this worldwide problem of physical inactivity and obesity. It is obvious that we don't have the solution yet and that it will take many decades to normalize our built up construct of a motorized, extensive energy overload - if this is possible at all. Importantly, one has to acknowledge that mild overweight does not harm much, but if the muscles of the human body are not used, more disease and a reduced life expectancy occur. This is evident for the adult population, but this relation seems plausible for children as well. In this article, we will cover physical activity and overweight in the school child including diagnostic criteria, their relevance for health and describe practical approaches that may help to make of each school child an active and "normal weight" human being.