PETER: You just think lovely wonderful thoughts and they lift you up in the air.

J. M. Barrie (1860-1937) Scottish novelist and dramatist [James Matthew Barrie]

Peter Pan, Act 1 (1904, pub. 1928)
    (Source)

In Barrie's novelization, Peter and Wendy, ch. 3 "Come Away, Come Away!" (1911), Peter uses the same words.