What is the meaning of a sincere intention when drinking Zamzam water, and what is an example of it?

The intention (niyyah) is the resolve to do something and the determination to perform it. If you intend in your heart to drink Zamzam water for healing or for any other purpose, then the intention has been formed. The meaning of a sincere intention is its purity and your conviction in the truthfulness of what the Prophet, peace and blessings be upon him, conveyed.