take nothing to heart; be disillusioned with; jaded

(adj.) nonchalant; phlegmatic; jaded/(v.) to remain calm even when something good or bad happens to you; to take nothing to heart to remain unbothered or unaffected by whatever that happens; to have a zen attitude about something; to see through the vanity of something; to be at peace with oneself no matter what is going on; to be disillusioned with something