Apparently, "euphoria" can mean a state of self-confidence. So, here's a snippet of Chelsea being confident.
Chelsea prepared herself for the obstacle course Danny set up for her in the park. She flexed her fingers, letting ectoenergy form in her fingertips. She went over the various ghost and human enemies in her mind. Her tail twitched like an angered cat. All in all, she felt ready for the task.
When Danny said, "Go!" she sprang onto the path of the obstacle course. Boards popped up with pictures of various people, and Chelsea shot the bad ones. At the same time, she dodged attacks from Danny. She contorted her ghostly body through narrow obstructions and repeated the entire process.
"Stop!" Danny shouted.
"How'd I do?" Chelsea asked, floating over to him.
"Perfect!" Danny said.
A feeling of warmth and euphoria swelled in her chest. "Sweet!"
"There's one obstacle left," Danny said.
Chelsea cocked her head. "What?"
"Me."
He attacked her without warning. They were close enough that Chelsea couldn't dodge or raise a shield. She took his punch to the gut and reeled back. Before she could make a retort, he was hovering over her, ready to punch again. This time, she raised a shield. His fist bounced against the shield, allowing her a moment to recover.
"You can't protect yourself forever," Danny said, maneuvering around her shield.
Chelsea fired an ectoblast at him, but he split his body so the blast went through harmlessly.
"Use your fists," Danny said. "I want to see how well you fight in close combat."
"You know I'm no good at that!" Chelsea said.
"Get better."
They continued to fight, but Danny held back. Chelsea got a few hits in, much to her surprise. Relief flooded her when he said to stop.
"You're improving," he said with a smile.
"Really?"
"Yup!"
Chelsea whooped and thrust her fist in the air. "Thanks, Danny!"