在英文中，“知足”可以用 contented 或 satisfied 来表示，“坚定”可以用 steadfast 或 resolute 来表示。因此，“知足且坚定”可以用以下几种表达方式来表示：
Contented and steadfast
Contented and resolute
Satisfied and steadfast
Satisfied and resolute
其中，contented 来自拉丁文 contentus，意思是“满足的”；steadfast 来自古英文 stedefæst，意思是“坚定的”；resolute 来自拉丁文 resolutus，意思是“坚决的”。
下面是一些例句，希望对您有帮助：
Despite his difficult circumstances, he remained contented and steadfast in his faith. (尽管处境艰难，他仍然知足且坚定地信仰。)
She was contented and resolute in her decision to leave her high-paying job and start her own business. (她坚定地决定离开高薪工作，开办自己的生意，并且对这个决定感到满足。)