彼は山にこもって修行している。
He has secluded himself in the mountains to undergo ascetic training.
若い僧たちは毎朝四時に起きて修行に励む。
The young monks rise at four every morning and devote themselves to their religious practice.
滝に打たれる修行は今も続けられている。
The practice of standing under a waterfall is still carried on today.