只有快乐、天真、狠心的人才会飞。

It is only the gay and innocent and heartless who can fly.

youdao

你失败了一次又一次，为什么你脸上没有痛苦，只有快乐？

You failed again and again, why don't you have pain but happiness on your face?

youdao

只有主人公先把那些恶龙制服，快乐的结局才有可能。

A happy ending is only possible because the hero has first vanquished the dragons.

《柯林斯英汉双解大词典》

And that was when I switched my concentration from computer science to philosophy and psychology with a single question: ? how can I become happier?

于是我将研究方向,从计算机科学转向了哲学及心理系,目标只有一个：,如何变得更快乐？

哈佛公开课 - 幸福课课程节选