Standard Phrase USED Frequently BY Mostly adults
(hello/good job) • It's a greeting phrase especially among co-workers and teammates. 疲れ is tiredness, and this phrase also acknowledges the other's hard work. You can just say 「お疲れさま。」to make it more casual.
「昨日5km走ったんだよ。」「お疲れさま。」
"I ran 5 km yesterday." "Good job."