从容不迫
Take things easy.
Take one's time.
Cool as a cucumber.

eg：No matter how difficult the job be, john always takes things easy and does it well.

中英俚语俗语来源：史记：“良尝闻从容步游下邳圯上。”

同义词：慢条斯理 Make two bites of a cherry.
反义词：迫不及待 Eat the calf in the cow's belly.