まだ起こってもいないことを案ずるよりも目の前のことに集中する。
過去を悔やまず、未来を憂えず、今に最善を尽くそう。

Do the best you can
Concentrate on what is in front of you rather than worrying about what has not yet happened. Do not regret the past, do not worry about the future, and do the best you can in the present.