Be (sitting) on top of the world phrase
To be extremely happy; to be extremely successful
She has been on the top of the world since Bob proposed to her.
I'm on the top of the world when I find out that I got the scholarship this term.
We were on the top of the world when hearing that her operation went well.
Kids were on the top of the world when I said we would take them to the theme park this weekend.
She seemed to be on the top of the world because of this sudden and unexpected success.
He is on top of the world after many years struggling in the profession.
Said when one is looking back on something enjoyable or worthwhile in the moment that it was happening even though it was impermanent
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
Meaning absolutely certain or without a doubt
I am as sure as God made little green apples that Peter's the one for you, you two make a beautiful couple.