I never let myself get too happy because I fear an equal and opposite state of sadness and misery.

我从不允许自己过分快乐。因为我担心为此付出同样的悲伤和难过。

youdao

I myself can not answer... I feel that I am a cheerful person, even in the sadness but also put on a happy, because I do not want to let people know I am sad, sad!

我自己也回答不了……我觉得我是一个开朗的人，就算在伤心也要装出开心来，因为我不想让别人知道我伤心、难过！

youdao

Strong and told myself, do not need to take to heart! After the birthday, let it take its own too. Happy or sad all right. Each year's time!

祝我生日快乐，坚强告诉自己，没必要去在意！以后的生日，就让自己陪这自己过。开心也好，伤心也罢。每年就一次而已！

youdao