是by ourself还是by ourselves?

Ourself is sometimes used instead of "ourselves" when it clearly refers to a singular subject. Some people consider this use to be incorrect.
(我们)自己; 在明确指单数主语时,有时用于代替ourselves.; 一些人认为此用法不正确.

Believe Ourself相信自己
Enrich Ourself充实自己
Exceed Ourself超越自我

根据语法来讲就只能用ourselves.
希望能帮到你!

by ourselves 是对的。
没有by ourself。

-self是个反身代词，指（谁）自己
此处是指我们自己，而“我们”是一个复数。所以用ourselves（ourself去f加ves）

后者

by ourselves