On top of the world
Definition 1 of 1
Pro Tip 1/3Metaphorical Height
This idiom metaphorically implies being at the highest point emotionally, not physically. 
When he won the lottery, he was on top of the world.
Pro Tip 2/3Figurative Success
Often used to describe the peak of success or achievement in one's life or career. 
Standing on the podium with her gold medal, she was on top of the world.
Pro Tip 3/3Temporary State
The feeling described is usually fleeting, not a permanent state of being. 
Scoring the winning goal, he felt on top of the world for the entire night.