If all is well with Doctor, then I would suggest when not riding, getting in some intense cardio. I do intervals on the treadmill and it really helps build the stamina. Run for 1 minute, walk for one minute. Do that for an hour. When that becomes easy, then run for 2 minutes, then walk for 1 minute. When that becomes easy...run 3 minutes, walk 1 minute. The walk minute allows you to rest muscles, while maintaining the heart rate. Its always nice to know that initially you are only 1 minute away from the walking portion.