yourself是反身代词,一般都放在句末,如：Please help yourself.（请自便）；也可以是固定搭配：by+yourself.

yourself

pron.你自己;您自己;你们自己;强调说话对象做某事;你;您

复数： yourselves

Ultimately, you'll have to make the decision yourself.

最终你还是得自己拿主意。

If you want another drink, just help yourself.

你要是想再喝一杯就请自便。

Try to think yourself into the role.

尽量发挥想象力，使自己进入角色。