Nobody gets used to rejection. You just get faster at recovering from it.

Nobody becomes immune to being turned down. What practice changes is the recovery time: the first one takes a week, the tenth takes an afternoon, and that improvement is real even though the sting is identical each time. Expecting to stop minding sets you up to feel like you are failing at something nobody manages.

Pay attention to how long it takes you to go again rather than to how much it hurt. Write down the date and the next attempt, and try to shorten the gap. If you are waiting to feel fine before applying for the next thing, you will be waiting a long while.