Definition
during my youth or the past era; when I was younger
在年轻的时候；在过去的年代
Kids take so much for granted nowadays; in my day, a new bike was a real treasure.
现在的孩子把很多事情都视为理所当然；在我那个年代，一辆新自行车可是真正的宝贝。
"Young people today don't know what hardship is," my grandfather said. "In my day, we had it much tougher."
「现在的年轻人不知道什么是艰苦，」我祖父说。「在我那个年代，我们的日子要艰难得多。」
In my day, we had to walk to school, rain or shine," she reminisced.
「在我那个年代，无论晴雨我们都得走路去学校，」她回忆道。