expression, godan verb (-ru)
throw out one's chest; be puffed up with pride
Literally to push one's chest forward, often used figuratively to mean acting confidently or proudly. Can be used in both positive (justifiable pride) and negative (arrogance) contexts.
彼は胸を張って会場に入ってきた。
He walked into the venue with his chest puffed out.
自分の仕事に誇り
I want to live with my chest held high, proud of my work.