Type B behaviour has given them a new sense of peace的意思

Type B behaviour has given them a new sense of peace的意思Heart attack victims who have tried to change their behaviour after their first heart attack report that Type B behaviour has given them a new sense of peace,freedom,and happiness.Not for anything in the world would they return to their old lifestyle,which held them trapped like prisoners in an unhappy world of their own making.Type B behaviour 是什么东西?