Brighten up (the) day verb phrase
To make one's situation better or more pleasant; to make one more happier
That good news has brightened up the day.
My kid's smile always brightens up my day.
Their unexpected help brightened the day.
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
The verb "brighten" should be conjugated according to its tense.
The figurative meaning of "brighten" - "dispel gloom from, cheer" dates from the 1590s.
A humorous way of saying that what one has said is just what they acknowledge and may not be entirely accurate
Mike: Have you returned from your vacation on the beach? Your skin seems to get tanned.
Jenny: My skin is always dark. That's my story and I'm sticking to it!