hitch one's wagon to a star

1. 立雄心
   He was a boy from a poor family who had hitched his wagon to a star and was determined to get a good education for himself.

   他是个有雄心壮志的贫家子弟，打定主意要受好的教育。

on the (water) wagon

1. 戒酒
   He's taken his doctor's advice very seriously and has gone on the wagon.

   他认真听取了医生的劝告，开始戒酒。

• on (or off) the wagon
  informal abstaining (or not abstaining) from drinking alcohol.