40 is nearly shorts and T shirt weather after a Michigan winter. Either a trainer or winter gear and tough it out. Riding outside in the winter builds up the strength of one's immune system, imo . Riding a trainer can be about 50% harder than over the road. Not much adjusting, shifting, or momentary breaks. Just the same old power generating position mile after mile .... going no where. Put a positive spin on it, turn the fan on and pretend you are riding into the wind.