a light heart
From Longman Dictionary of Contemporary Englisha light hearta light heartliteraryHAPPY someone who has a light heart feels happy and not worried I set off for work with a light heart. → light-hearted → lightExamples from the Corpusa light heart• He sat down to his dinner with a light heart.• The breakdown of his marriage to Anna and remarriage to Wendi Deng were not done easily or with a light heart.• I pitched into the chores with a light heart, singing to myself as I worked.