Worry

like a cat on a hot tin roof

Meaning: in a state of agitation.

Example: The coach acted like a cat on a hot tin roof throughout the game. Read on

rest assured

Meaning: emphasizing that there is no need to worry

Example: You can rest assured that the transaction will be completed by the close of business today. Read on

never mind

Meaning: to urge somebody not to worry about something

Example: Never mind, I will do it myself. Read on