expression, i-adjective
young at heart
Describes someone whose spirit, attitude, or interests are younger than their actual age. Often used as a compliment.
祖父は80歳だが、気が若くてよく新しいことに挑戦する。
My grandfather is 80, but he's young at heart and often tries new things.
彼女は気が
She's young at heart, so she enjoys talking with young people.