"Should" rules — rigid expectations about how you, others, or the world ought to behave — are one of the most consistent generators of anxiety and resentment. Here is how to identify them and work through them.
Should statements are exactly what they sound like: concentrating on what you think "should" be rather than what actually is. They create a constant gap between expectation and reality, and every time that gap shows up, the emotional cost is paid in anxiety, guilt, frustration, or resentment.
Albert Ellis called this pattern "musterbation" — the chronic application of "must", "should", and "ought" to situations that may not warrant such rigid rules. The Fallacy of Fairness — the belief that the world should conform to your personal sense of what's fair — is closely related: it almost guarantees frequent disappointment, because the world routinely doesn't.
"People who go through life applying a measuring ruler to every situation, judging its fairness, will often feel badly — because life simply doesn't conform to our rules as often as we'd like."
When a should rule is violated — by yourself, by others, or by circumstances — the typical response is what we can call Negative Reflection: dwelling on how negative the situation was and magnifying it. This is itself a cognitive distortion (magnification), and it tends to make everything worse without producing any useful outcome.
This technique can be used whenever a person or situation bothers you. It converts negative experiences into something you can actually learn from.
If yes — what could you have done differently? If no — could there have been a better way to handle the situation, with hindsight?
What rigid expectations are driving your frustration? "They should have..." "I should have..." "This shouldn't have happened..." Name them explicitly.
Not resignation, but accuracy. "I would have preferred..." or "It would have been better if..." rather than "it should have been..."
What is the useful takeaway — regardless of who caused the problem? Every experience has a lesson available, and finding it converts a purely negative event into something with value.
The point is not to assign blame or avoid responsibility. It is to stop being controlled by unexamined should rules, and to extract something useful from difficult experiences rather than just dwelling in them.