It's important to stop doing something early when you think you want to do just a little bit more, and move on to the next thing you have to do.
ご質問ありがとうございます。
"It's important to stop doing something early"＝「何かを早く止めるのが大事です」
"when you think you want to do just a little bit more"＝「あなたが（それを）もう少しやりたいと思ったとき」
"and move on to the next thing you have to do."=「そして次にするべきことに移ることです。」
ご参考になると良いです！
アメリカ合衆国 
