NEED SOME ADVICE? 😤🙄😒😭

Im a sales representative , and costumer are sooo disrespectful at times before i wasnt pregnant i wouldn't say anything i would just stay quite bc i knew it wasnt worth my time arguing back ... but now i feel like they can piss me off so easily now , but my questions is do any of  yall know how to just let it go and not talk back ? Like how do yall do it ?