Tā jīnnián wǔshí, guǒrán wǔshí ér zhī tiānmìng, xīntài yuèláiyuè pínghé.
He turned fifty this year - truly 'at fifty, knowing heaven's will' - increasingly at peace with himself.
Tips
history
From 《论语·为政》 (Analects). Part of Confucius's six-stage autobiography: 吾十有五而志于学，三十而立，四十而不惑，五十而知天命，六十而耳顺，七十而从心所欲不逾矩。 知天命 became a set phrase for being fifty years old and is still used in birthday congratulations and obituaries.
usage
Always part of the Confucian age-set. 知天命之年 = 'the age of fifty' is a polite phrase in modern speech.
