There’s a difference between a “can do” attitude and a “must do” attitude.
The can do attitude is based on confidence, competence and realism blended with optimism. The must do attitude is based on anxiety, resentment and a false belief that the essence of goodness lies in selfless service, rather than in pride-inspired quality.
The can do attitude is the term for the sum total of an attitude that makes an individual or a society great. The must do attitude is found in an individual or a society in decline, or that never had much to offer in the first place.
The can do attitude takes humanity to the highest possible. The must do attitude is the basis for slavery, either the political kind (imposed from the outside) or the psychological kind (imposed from the inside).
People with the can do attitude move towards achievement and satisfaction. People with the must do attitude might achieve some success, but never their full potential–and they never enjoy the satisfaction of that achievement.