1 general:: Phrase(s): walk on air Fig. to be very happy; to be euphoric. • Ann was walking on air when she got the job. • On the last day of school, all the children are walking on air.
McGrawhill's American Idioms And Phrasal Verbs
2 general:: Feel elated or exuberantly joyful, as in She was walking on air after she found out she'd won the teaching award. This metaphoric term likens feeling happy to floating. [Late 1800s]
American Heritage Idioms