to be very happy and excited because something very pleasant has happened to you.
When the doctor told me I was going to have a baby, I was walking on air.
be walking on air
To be extremely happy. I've been walking on air ever since I got engaged!
be walking on air
If you are walking on air, you feel very happy or excited. As soon as I knew I was in the team I was walking on air. Note: You can also say that you are floating on air. I can't believe that I've won. I'm floating on air!