idiomthinkingandbehavingas if you areyoungerthan you really are:心态年轻Dad may benearly90 but he's stillyoungatheart.爸爸可能年近90了,但他心态依然很年轻。SMART Vocabulary: related words and phrasesPhysically and mentally mature & immature
adult
adulting
ageing
an old/a wise head on young shouldersidiom
babyish
childish
grown up
immature
immaturity
infantile
juvenile
mature
maturity
overgrown
petulance
petulant
petulantly
puerile
puerility
sophomoric
See more results ?(Definition ofyoung at heartfrom theCambridge Advanced Learner's Dictionary & Thesaurus? Cambridge University Press)#https://dictionary.cambridge.org//dictionary/english/young-at-heart##