If you ever find yourself at an outdoor market in Germany in the winter you'll see people strolling along, bundled up, with a steaming mug of glühwein in hand.
Now that's my idea of shopping.
Heat the red wine gently in a crockpot.
Cut the lemon into slices and add to the wine. Then add the cinnamon, cloves, sugar, and a little cardamom or ginger to taste.
Heat for about 5 minutes (do not boil!) and then let stand for about an hour. Before serving, reheat and strain. Serve in prewarmed glasses or mugs.