To do something for oneself in English, one can say "to do something for oneself" or "to do something on one's own." This phrase comes from the idea of taking responsibility for one's own actions and not relying on others to do things for you.

Here are some examples in English:

I'm going to the store to do some grocery shopping for myself.

I like to do things on my own, without needing help from anyone else.

She's been working hard on her own project, without any help from her colleagues.

Here are the translations of the examples in Chinese:

我要去商店买点东西做我自己用。

我喜欢独立完成事情，不需要别人的帮助。

她一直在自己的项目上努力工作，没有得到同事的帮助。