Depressed because ability and desire do not match.
In Da Sheng, Chuang Tzu gave us a suggestion: if you feel that what you want in the world is far greater than what you need, and your ability is not enough to support your desire, you should do a little subtraction.
This is really not easy for modern people.
Trabecula has an algorithm, or formula. I think the so-called depression means that your desire is greater than the chance given to you by the world. When what others want you to do is far less than what you want to do, depression will form.