A good mathematician is lazy, but in a constructive way.
What's terrible is to pretend that second-rate is first-rate. To pretend that you don't need love when you do; or you like your work when you know quite well you're capable of better.
The purpose of life is not to be happy. It is to be useful, to be honorable, to be compassionate, to have it make some difference that you have lived and lived well.