Be who you are and say what you feel because those who mind don't matter

and those who matter don't mind.

~ Dr. Seuss

做自己想做的，说自己想说的，因为那些介意的人无关紧要，

有关系的人是不会介意的～

补充如下：

Those who mind don't matter, those matter don't mind.

Bernard Baruch in response to a question how he handled the seating arrangements at his dinner parties, the full response was：

”I never bother about that. Those who  matter don't mind, whose who mind don't matter."

It has also become part of a larger expression, which has been commonly attributed to Dr. Seuss, even in print, but without citation of a specific work: 

"Be who you are and say what you feel because those who mind don't matter and those who matter don't mind.“