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to be in high spirits; to be full of vigor (vigour); to be enthusiastic; to be eager; to stretch to breaking point
入社一年目の彼は新しい仕事に張り切っている。
In his first year at the company, he is enthusiastic about his new job.
彼女は友人が来るので張り切って豪華な料理を始めた。
She eagerly started cooking.
体を壊すからあまり張り切りすぎないでね。
Don't get too enthusiastic.