Bridge to Terabithia
How we cite our quotes:
He watched the car go out of sight and then turned and ran with all his might to the house, the joy jiggling inside of him so hard that he wouldn't have been surprised if his feet had just taken off from the ground the way they sometimes did in dreams and floated him right over the roof. (10.70)
This pure "joy" is, unfortunately, short-lived. Yet, maybe it's only because it's short-lived that it's so deeply felt. Jess is so overcome with this "joy" that he practically flies, having so much feeling flood through him that he almost comes off the ground. This happiness makes him run faster.
If he got up now and went down to the old Perkins place and knocked on the door, Leslie would come to open it, P.T. jumping at her heels like a star around the moon. It was a beautiful night. Perhaps they could run over the hill and across the fields to the stream and swing themselves into Terabithia. (11.14)
Now Jess is trying desperately to make magic happen, when before he thought he couldn't. It's as though thinking about it hard enough will not only get him into Terabithia, but also will bring back Leslie, alive again, so they can go together.
She had tricked him. She had made him leave his old self behind and come into her world, and then before he was really at home in it but too late to go back, she had left him stranded there – like an astronaut wandering about on the moon. Alone. (12.17)
Jess is angry with Leslie for transforming him and then up and leaving. It's a natural stage of grief. He's mad at her because she was taken from him after totally changing him, but not quite finishing the process – leading him partway and then disappearing. He can't unlearn or change back to the way he was, but he also doesn't feel like he can move forward.