Don’t smoke, don’t drink or eat to excess – these are health mantras most of us are familiar with. But there’s another one to add to this list: don’t sit for too long. But why would sitting cause health problems? Don’t smoke, don’t drink or eat to excess – these are health mantras most of us are familiar with. But there’s another one to add to this list: don’t sit for too long. But why would sitting cause health problems?