You might think that casting calls are the most fun you can have without actually acting, but think about it, you actually do have to act in casting calls, and if you really want a part, you have to act really well. The only way you are going to get a part is if you act as if you are actually right up on stage or right under the lights with the cameras rolling, because the casting directors have seen it all, and if you're slouching, the next thing you'll hear is "next!"
Casting calls are part of the great tradition of acting, and you should really look forward to them as a learning experience and a chance for you to practice your chops in front of people who know a good performance when they see one. Casting calls are also your only way into getting the roles that are out there, so you'd better learn to enjoy them now if you don't already.
The real joy of casting calls is waiting it out with all the other actresses and actors, this is when you get to meet your peers and learn from them by listening to their stories and hearing what they have to say about their experience going to casting calls. They may have some good advice or a helpful anecdote that could help you do better in future casting calls!