It is foolish to ignore the advice of your doctor.
Reggie is ordering a dessert at a restaurant, though his doctor has warned him he needs to lose weight, or he may have a heart attack.
Reggie wants to eat dessert.
Reggie orders a small cookie and eats only that for dessert.
Reggie orders a large ice cream sundae and eats the whole thing.
Reggie starts losing weight and becomes more healthy and fit.
Reggie gains more weight and eventually has a heart attack.