A young idler, an old beggar.
少壮不努力，老大徒伤悲。

As heroes think, so thought Bruce.
英雄所见略同。

An apple a day keeps the doctor away.
一日一个苹果，身体健康不求医。

All time is no time when it is past.
机不可失，时不再来。

All rivers run into the sea.
殊途同归。

A letter from home is a priceless treasure.
家书抵万金。

A guest should suit the convenience of the host.
客随主便。

A fall into the pit, a gain in your wit.
吃一堑，长一智。

A contented mind is a continual / perpetual feast.
知足常乐。

A common danger causes common action.
同舟共济。