There is no shame in not being a natual athelete, or an athelete at all. I know a guy who is a superfit rider, used to ride road. He had a heart event, and real or imagined, got too spooked to ride the roads, thinking he'd have the big grabber and no one would be there to save him. So he got a high end indoor trainer, with a video screen and rides you can program in. He rides a couple hours every day at home. Not for me, but once a year he is fit enough to ride the Seattle to Portland 200 miler. Its his one ride every year. Maybe your friend can just ride at home. Anything over an hour a day doesnt help your cardio fitness an more than riding all day, anyway.