What Youth deemed crystal, Age finds out was dew.

Some of what you were certain about turns out to have been temporary rather than solid. A conviction, a friendship, a plan can look cut and permanent while you are inside it, and then be gone by mid-morning. That is not evidence that you were foolish. You could not have known the difference yet.

Hold your current certainties a little more loosely, though not less warmly. Ask which of them you would still choose knowing they would not last, because a few would be worth every hour anyway. The rest you can set down without turning on the person you used to be.