While a classical and somewhat literary term, 本心 is still used in modern contexts, especially when discussing morality, integrity, and authenticity.
In Ethical Discussions: It's frequently used when someone makes a decision against their principles for personal gain. You might hear someone say, “违背本心 (wéibèi běnxīn) - to go against one's original heart.”
In Art and Career: An artist who refuses to create commercial work they don't believe in is said to be “staying true to their 本心.” Someone who quits a high-paying job to do something more meaningful is “following their 本心.”
In Self-Help and Spirituality: The term is common in books and lectures about mindfulness, personal growth, and finding one's purpose. The goal is often framed as “找回本心 (zhǎohuí běnxīn) - to find one's original heart again.”
It is generally a formal and positive term, carrying a sense of weight and sincerity. You wouldn't use it for trivial, everyday decisions.