Unupsettable - this is not, yet, a word in the standard dictionary. But, if Buddha were to review any dictionary, he would have surely liked this word to be the most important word in the entire dictionary and in any language for that matter.
There is a very seldom quoted Buddha saying. Goes something like this - you get upset because you are upsettable. Nothing else can cause your getting upset.
This goes so well with stimulus and response theory of human behavior. Our getting upset is our response to some stimuli. Most people say, if you never get upset, you must be dead. But, Buddha says, it is possible. He says if you choose a different response to the stimulus, it is possible.
Many of equate getting hurt (physically or emotionally) as getting upset. Hurt is a feeling. Being upset is a state. You can not avoid getting hurt.You can not stop from feeling whatever you feel. Senses will register the stimulus, whether we like or not. But, we can choose a different response. If you are hurt, fine. It feels bad for a while. But, if you continue to brood over it, you are slowly changing that from hurt to longer lasting state of upset. We should avoid that.
Buddha used to simply brush off if anybody came saying that so and so upset him or her. He would bluntly say - you get upset because you are upsettable.
Work on your mind. That's your engine. Something is out of tune there. Make the necessary correction and slowly and surely you will stop getting upset. You will enjoy all the emotions in adequate depth but you will not get upset. That's the ultimate goal. Even for beginner, you will surely be able shorten the length of time you remain upset. Earlier it may be months, slowly it becomes days, then minutes, then seconds and then just a flash and you are back to your normal self.
We spend so much time taking care of the body but mind is allowed to be on its own. This is like taking really good care of the car body but totally ignoring the engine. There is funny saying - embroidering the seat-belt when the engine needs a major overhaul.
Body should be cared for and must be kept in best possible condition. However, ignoring mind will be at our own peril. Else we will end up with an equivalent of a car with Ferrari body and a Ford engine. Sound mind in sound body is not necessarily true. Sound body is a prerequisite for sound mind. But, it does not guarantee it. But sound mind will help make the body sound regardless of whatever may be the condition of the body. If you read some impressive biographies like Viktor Frankl's 'Man's search for meaning' etc., you will see how poor was their physical health. It was the soundness of their mind that helped them live through those nightmarish years.
So, start making your mind unupsettable. Mindfulness is a good place to start. Mindfulness - fancy word for living in the moment. Not in the past and not in the future.