not have a care in the world
sans-souci
worryless
carefreely
let it all hang out
lark
wanton
rollickingly
boisterously
with gay abandon
happy-go-lucky
happy as Larry
happy as a clam
blithesome
happy as a jaybird
lotus-eater
gather rosebuds
lighthearted
blithe
lightsome
light-hearted
dolce far niente
bindaas
rollicking
let oneself go
blithely
angstless
unbelt
contrafreeload
unfreeness
get one's ya-yas out
at peace
unhurried
go bonkers
fancy-free
devil-may-care
carefree
unworried
untroubled
rilek
relaxed
get down
toddle
sunly
breeze
jaunty
chipper
melt
mellow out
unspool