see under heavy heart.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
Examples from the Web for light heart
She smiled to see his light-heart joy, and said again, as if to herself, "In a while I shall cry to himI dinna need him yet!"Cleg Kelly, Arab of the City
S. R. (Samuel Rutherford) Crockett