One of the best pieces of advice I ever received in this business (about rejection) came from a guy named Jack Angel. He’s famous for his brilliant voice work in shows like G.I. Joe, the Smurfs and the feature films A.I. and Toy Story. The first week I signed with my agency he told me "The audition IS the job." If you have the opportunity to audition in the first place, there really is no way you can feel rejection unless you choose to. Not if you truly take it from that perspective. If you treat every single audition as though that was the final gig, you’re actively doing the thing you say you want to do!. Treat it as if it’s the only time you're going to have with that character or that line or that script and then: let it go. If you book the job later on—great! Bonus! This really helps to alleviate some of the pressure that you might put upon yourself. I audition FAR more than I book, like at a ratio of 30-50 auditions per each booking, and I’ve been doing this for decades! Do the best you can do. Do a great audition and then let it go.