a courteous manner(礼儀正しい態度)や display a courteous attitude to ~(~に対して礼儀正しい態度を示す)といった感じで使えますね。
Being courteous is a simple yet powerful way to brighten someone's day.
(礼儀正しくあることは、誰かの1日を明るくする、シンプルだが強力な方法である。)
Being courteous is an essential skill that everyone should practice in their daily lives, as it can have a significant impact on how we are perceived by others.