Why am I exhausted from making every candidate feel valued?

You treat every candidate like a person, even the ones you will never hire. That costs you something each time. No one puts it on a scorecard. You feel the cost anyway, and you are right to — it is real work, even without a line item. But look closely at what you have confused. You are not tired because warmth is heavy. You are tired because you never decided how much of it to spend, or on whom, or when to stop. You have given it the way water runs downhill — toward whatever slope appears, without judgment, until you are empty. What is not in your power is whether anyone counts this labor. It likely never will be counted. What is in your power is the measure — how much you extend, in what form, before you keep the rest for yourself.