to perform duties regularly for payment

काम करना

English Usage: I work at a software company.

Hindi Usage: मैं एक सॉफ़्टवेयर कंपनी में काम करता हूँ।

the speaker or writer

मैं

English Usage: I enjoy reading books.

Hindi Usage: मुझे किताबें पढ़ना पसंद है।

activity involving mental or physical effort done in order to achieve a result

कार्य

English Usage: My work is very fulfilling.

Hindi Usage: मेरा कार्य बहुत संतोषजनक है।