Insouciant (in·sou·ci·ant)
adjective
showing a casual lack of concern; indifferent.
a relaxed and happy way of behaving without feeling worried or guilty: I admired his youthful insouciance
Insouciance has roots in the French in, meaning "not," and se soucier, meaning "to care," giving the English word its "uncaring" meaning. Insouciance can be a positive state — like the childlike insouciance you feel when you are watching cartoons instead of paying your bills.