complacent, permissive, amenable, breezy, carefree, casual, complaisant, devil-may-care, even-tempered, flexible, free and easy, hang-loose, happy-go-lucky, insouciant, laid-back, lazy, lenient, low-pressure, mild, moderate, nonchalant, patient, placid, relaxed, serene, tolerant, tranquil, unhurried, uninhibited. OK I got this list from thesaurus.com !!

relaxed, laid-back, comfortable OPP uptight