1) Blithely 2) Briskly 3) Gaily 4) Gayly 5) Gladly 6) Happily 7) Jubilantly 8) Mirthfully 9) Playfully 1) Blithely 2) Carelessly 3) Casually 4) Gaily 5) Gayly 6) Happily 7) How to roll along 8) How we roll along 9) In a joyous manner 10) Jubilantly 11) Mirthfully 12) One way to row a boat 13) Unthinkingly 14) With happiness 15) Without a care in the world 
• (adv.) In a merry manner; with mirth; with gayety and laughter; jovially. See Mirth, and Merry.
Mer'ri·ly adverb [ From Merry .] In a merry manner; with mirth; with gayety and laughter; jovially. See Mirth , and Merry . « Merrily sing, and sport, and play.» Granville. 
mirthfully adverb in a joyous manner; `they shouted happily`