optimist; easy-going person
Describes a person who habitually looks on the bright side and does not worry much. Often carries a positive, light-hearted tone.
He is an optimist who stays positive in any situation.
楽天家の彼女は、失敗してもすぐに気持ちを切り替える。
Being an easy-going person, she quickly bounces back even after a failure.
He's a natural-born optimist and always has a smile on his face.
My mother is such an optimist that she bounces back quickly even after a failure.