Timely subject. Last winter I did not do any exercise of any sort and struggled getting into riding condition in the spring. This winter I did only walking for an hour in the mornings 5 days a week and lifting light weights high reps 3 days a week.
Jumped on the bike this past weekend and it felt like I picked up where I left off in the fall. I feel great and didn't have to do any indoor rides or cold snowy winter rides.
The upper body strengthening seems to have made the difference.