During the saddest moments of my life I was focused on myself. During the happiest moments of my life I was focused on others. Next time you find yourself in a morass of negative thoughts about yourself, may I recommend a distraction? Most anything will do. Go do something physical or read or watch or listen to something or do something nice for a friend. Turn outward.
This distraction technique isn't a pass to avoid doing useful introspective work. But thought spiraling isn't useful. Snapping yourself out of that trance, putting some space between you and what upsets you, helps to reduce feelings of overwhelm and urges to indulge compulsive behavior.
I recently heard about Dialectical Behavior Therapy (DBT), which helps people to develop healthy ways to cope with stress, regulate their emotions, and improve their relationships with others. If you find distraction to be a useful technique during low moments, I suggest reading about DBT's other distress tolerance skills.