It doesn't make sense to me but...
Psychologists have discovered that the best strategy for career success is to over-promise and under-deliver.
This, of course, flies in the face of the idea of under-promising and over-delivering.
It might feel better to over-achieve, but research suggests that you’ll get farther in your career, faster, if you raise great expectations and make yourself seem more competent -- even if you can’t deliver.
Who knew? Probably the people who are already doing it : )
I wouldn't run this by your boss however!