Enthusiasm with 乗り気
乗り気 is eagerness or enthusiasm of somethihng.
Dictionary Definition
進んでやってみようという気になること。
Being interested in voluntarily trying and doing something.
Goo Dictionary
Examples
Enthusiasm about a trip with 乗り気

Al shows Akari and Aika around his workplace. Afterwards, Akari thanks Al for showing them around and she prompts Aika to do the same.
- 藍華:
- 「まあ あんまり乗り気じゃなかったケド思ってより悪くない小旅行だったわよ」
- “Well, I wasn't that ethusiastic, but the excursion wasn't as bad as I thought it would be.”
- 「あんたのおやじっぷりはどうかと思うケド」
- “I still have a problem with your old man style, though.”
Enthusiasm for a group outing with 乗り気

Kikuchi asks Futaba out. He says if she prefers, they can invite their friends along as well.
After school, Futaba brings it up with her friends. Yuuri says she’ll go if Kikuchi’s friend Uramiya is there.
- 悠里:
- 「でも双葉ちゃんが乗り気じゃないんなら…」
- “But if you're not interested...”
- 双葉:
- 「うーーーん」
- “Mm...”
Enthusiasm for shogi club with 乗り気

Sakurako forces Takeru to join the shogi club. When he suggests she join as well, she refuses and tells him not to go either, or else he’ll be in the way there.
- タケル:
- 「乗り気じゃなかったが入部した以上はしっかり活動する!」
- “I wasn't enthusiastic, but now that I'm in the club, I'll work hard!”
- 「それが男ってもんだ!!」
- “That's what it means to be a man!!”