3. Appeal to his pride: “You’re a capable guy; you can manage your weight.”
“If I thought that being overweight proved I was incompetent, I’d definitely feel I had to do something about it.” For guys with the urge to get ahead, appealing to their self-respect can be effective. Using secondhand business knowledge, like “You know, the ability to self-manage is the basic requirement for a leader,” may also hit home for him.