When you get angry over small things, ask yourself how important it is. How bad is it, really?
When you are anxious over something that may or may not happen, ask yourself::
- What is the chance of it happening? (Probably very small, because anxiety attacks tend to be imagined scenarios with lots of detail in them, which makes them seem realistic while actually the more detailed they are, the less chance there is of them coming true.)
- How bad would it really be if it did happen?
- What would the price be for you to minimize the chance of it happening? "Price" in terms of worrying about it, doing things you don't want to do, not doing things you do want to do, having to buy something, etc.
You need to make a very conscious, deliberate decision to ask yourself these questions, else your anger/anxiety will absorb you entirely.
Being 21, you'll probably live at least another 50 years or so. Probably more if you accept that you can't hope to predict or control more than a bit of what will happen.
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There is nothing that is uniquely and invariably human.