Depression is a negative thought loop that in the moment feels impossible to escape. Irrational thoughts seem rational. In a clinical sense depression (as a disorder) may be the cause. It persists even when your quality of life is good. That said, depression can also be an effect (triggered by a traumatic experience).

Distancing yourself from your feelings may help temporarily, drugs do that.

Occupying your mind with activities that provide a positive reward loop and positive feeling (hobbies, exercise, social activities) likely makes the most difference.