During winter, millions of people catch colds. Most recover quickly — yet few know that viral infections can cause heart inflammation if you don’t fully rest. A hidden myocarditis may trigger life threatening heart rhythm problems. This report follows 28 year old Folke, whose supposed cold was diagnosed as myocarditis at Kiel University Hospital. We explain which warning signs should never be ignored, how doctors confirm the diagnosis, and why strict rest — sometimes for months — is crucial to prevent long term damage.