Auditioning is exciting. Fresh choices, lines, a very small audience in the form of your casting director and his (or her!) minions, in a very small room. I love it. I mean, I don't love the initial nerves, but the second I walk through the door, the audition starts and my anxiety dissipates. You give it your all and you rock it.
And when you get a callback, saying you've got the talent they were looking for?
There is nothing sweeter—aside from actually being cast, of course.
In one of my acting classes a few years back, my mentor told me, "Talent gets you the callback. TYPE gets you cast."
Meaning, you could have absolutely NAILED your audition: you emitted the very essence of what they were looking for in the character they want to cast, BUT, if you're not WHAT they're looking for, then it really doesn't matter—and that sucks, because you literally can't control that. You might get rejected for being too short, too tall, too auburn, too blonde, too awkward, too this, too that and IT. SUCKS. I just got rejected from one of the roles I'd had a callback in. No explanation as to why (which is expected, but still). It stings.
But, perseverance pays off and eventually I'll be cast because I gave them what they wanted, and I fit the physicality of the character they're looking for.
Keep moving forward.