@IlayWainer atrophy doesn't happen overnight, muscles simply dont work that way. he does, however, have to have regular and near-constant exercise (dude basically walks a marathon's worth some days with how much he spends pacing)
The guy is like 80 years old now and his body has slowly gotten worse from a combination of three or four autoimmune diseases, one of them unnamed and potentially unique to him. He's still alive and doing a great job with his health. but yeah he has difficulties, probably gonna retire in a year or two due to mental degradation from having lived so long. real champ, one of the coolest people I've known in my life, taught me many things about how to live.