开始做某事

It´s important to remember why you started doing something.

重要的是你要记住为什么开始做某事。

I´d like to start by doing.

一旦你开始做某事，你就必须做到底。

If you go back to square one it means you have to start over on something.

如果你回到一圈，意思是你重新开始做某事。

Have you ever done something in the heat of the moment, and regret it later?

你有没有过曾一时兴起开始做某事，不久又没了热情？

It means that the first person who does something early has the best shot at success or that some opportunities are available to the first competitors.

意思是说，最先开始做某事的人容易成功。或者说最先行动的竞争者好机会更多些。