1
What did I realize? I realized that the subjectiveness of my perception is different from the external assessment of me. In fact, me subjectively almost never changes. I am the same person when I was 10, 11, 15, 17, 19, and 21. My identity has so far stayed mostly the same. So you can't base yourself on external rewards or failures, nor can you base yourself on the illusion of other people's success. You should base yourself on yourself if you are doing some planning. I am not a better person if I win dramatically, nor am I a worse person if I lose hopelessly.
However, externally, it is very difficult to communicate your subjective feelings about yourself to someone else. When you are communicating to someone else, you must step out of your immediate mental space and use empathy to communicate your thoughts from their perspectives. You must compartmentalize yourself, at least to the vast majority of acquintances. Otherwise, others will simply not understand. If I say I did something easily and dismiss the difficulty, it comes off as snobbery. If I convinced myself to quit a hobby or chose a major, while the other person likes doing it, the immediate instinct is to deny it. This comes off as rudeness or lack of empathy. It does not mean to be insincere and stop expressing your personal opinions, but rather to express it so that the other person can understand you with their living experiences.
2
What is in my identity? I believe the ultimate identity is not based on a list of awards or diplomas. The ultimate identity is what a person is going to do when the basic living expenses are covered and there are no objective rewards for doing anything. In such situations, sincerity and passion come through. If you base yourself exclusively on your job title or your income, it is an illusion of identity. If someone's basic needs on Maslow's hierarchy are satisfied, and they still have nothing else to do but scrolling shorts or gaming, we say the person's identity is not fully formed, or they are devoid of an identity. Hedonism is usually an reaction, not the destination.
To truly understand what it is, we can separate activities into 2 categories. One category is "ephemeral", the other category is "permanent". Here are some simple analogies. A captain stands with their ship. A general stands with their fortress. An artist creates in exile. A lifelong adventurer is always on the move. A brilliant athlete's entire life might always be around the sport, such as coaching, commenting, and shows.
You do it because it is part of your core identity, regardless of external rewards. External rewards matter, but most of the motivation are internal.This does not mean you should be dogmatic, the field might evolve and you should adapt. It is just about dedication. I believe that to be good at something, it have to be "permanent". There can only be very few things truly "permanent" for a person.
3
Can't you be "spontaneous" when you are free? Of course you can. You can suddenly decide to travel somewhere, learn a new skill, or do "eat, pray, love". Having a core identity does not erase spontaneity or adaptability. It does not mean you have to be a nerd or erase your personality.
However, you have to be very careful if you want to merge spontaneous things into your core identity. From my experience, usually you can't merge them. A summer camp ends, a flight returns home from a trip, and old contacts in different cities on different paths fade away. We call this "fleeting beauty". It is beautiful because it is fleeting.
There are situations where we want to live in a small city by the sea and read literature. But if you actually have the financial freedom to live there, it becomes empty in several days.
4
Getting old mentally is when you do not have an identity at all and you lose the ability for spontaneity. In this sense, someone can be old at 20, while someone can be young at 95 with a purpose, till the day they pass away.
Getting old mentally is not when your identity solidifies. In fact, if you base your identity on external measurements and conditions, which does sometimes solidify as you age, you may actually lose part of your identity.
5
A person's identity is not necessarily related to their external moral righteousness. Objective morality does not exist, and morality is usually a social construct. A conventionally immoral person can still have an intact identity, as the argument goes that the identity exists largely outside of social judgements.
However, a person's identity is moral subjectively.