I deal with rejection by telling myself that the person who rejects me, or criticises me, doesn't deserve me! Cos I know that I've given my utmost in all I do, and if you don't appreciate it, it's your lost - then I move on to locate the next person who deserves my focus.
If it is your boss, then try to determine his or her thinking and psyche, to understand where the thots are coming from, is there a higher reasoning for him reacting that way, or perhaps he has misunderstood your actions or something you said. I will go take a long run as I find running helps me to sort out my thots better.
Once I think I understood their position, I attempt to put myself in their shoes and view the situation from that perspective. Perhaps I may react that way as well if I'm in that opposite position.
Whatever it is, you MUST NEVER show up any temper tantrums or sulk or worse still spread lies and rumours and negativities about the person who reject you. Cos I always believe, "whatever goes around, comes around". There is a chinese saying which translated says "Though the seas are so huge, ships still collide. Tho' the skies are so immense, planes still collide." Tho' you may spite another and attempt to move away from the one, your day will come!"
Move on with life and there will definitely be opportunities out there for you!
My "five-cents-worth"!
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Kayceezharold
The World Thru Kayceez Eyes Earn As You Learn