It's my birthday and I'm feeling a bit sad.

今天是我的生日，我感到有些悲哀。

youdao

And, although it's a very sad time for people here, I think people are feeling a little bit resigned.

NPR: U.S. Auto Industry Still Reeling

You have to let yourself feel unhappy for a bit, and if you recognize your feeling and acknowledge it, you can have your sad moment and then move on.

FORBES: Do One Thing at a Time