Volleyball players often face the pressure of having to execute a good serve at a key point in a match. To simulate this type of situation in practice, Karch Kiraly has his players hit serves while teammates heckle them.
To handle this pressure, it helps if the server has a short saying that they can repeat to themselves that keeps them focused on the task. Former USA player Reid Priddy would say, "Just me and the ball."
Whatever saying you come up with, the key is to block out the noise and perform the skill without fear of failure.