ichidan verb
put on a bold front; show determination; act tough
Used when someone visibly strains or puts on a show of strength or confidence, often to impress others or hide weakness. The 〜てみせる construction adds a nuance of demonstrating or performing the action.
彼は痛いのを我慢して力んで見せた。
He put on a bold front, enduring the pain.
弱音
It's his style to show determination without complaining.