Reaching for the moon by S. J. Barratt

Standing at his window, Alex yearned for the moon.
A shooting star beckoned. Alex jumped.
Soaring higher, he reached Pegasus, the winged horse. Together, they flew, laughing, exploring the cosmos. At dawn, Pegasus descended, advising, 'Always aim for the moon, Alex. Even if you miss, you'll land among the stars.'