Keep smiling informal verb phrase
To maintain a positive and optimistic attitude or demeanor, especially in the face of hardship or adversity
I know you're worried about your father's health, but you try to keep smiling.
A: My first day at work was bad. B: Keep smiling! Don't be discouraged! You will get used to it soon.
To make someone feel more confident or happy, especially when they thought that they can't achieve what they want
Happy or cheerful; in a good mood
To smile broadly
If you fall for someone's trick the first time then they are at fault.
Are you going to mess with me again? Fool me once, shame on you; fool me twice, shame on me.