I dropped my backpack, shrugged off my coat, and hopped on the exercise bike. Charging the batteries was usually the only physical exercise I got each day. I pedaled until the meter said the batteries had a full charge, then sat down in my chair and switched on the small electric heater I kept beside it. I pulled off my gloves and rubbed my hands in front of the filaments as they began to glow bright orange. I couldn’t leave the heater on for very long, or it would drain the batteries.