Thanks for the replies everyone!
John isn't my husband, but a dear friend. He is much older than me and I consider him as a kind of second father. We work together (that is where we met) and that is why I see how he manages working.
There is no doubt that work is very important to him. He is a boss so it is difficult for him to limit the work, although his boss has said they would allow him to work part time if it suits him better. They will do everything to keep him.
To find the balance is difficult and I would like to know, if it has any concrete impact on the disease. Luckily his work isn't physically hard so it doesn't harm the bones, but I don't know what stress could cause? Has there been any studies of that?