You ever been at such a mental low for no reason?

Like you’ll be in the middle of work and you’ll just suddenly start feeling really down for no reason, just reflecting every negative experience in your life til that point?

Does it ever drain you physically as well? Like you start moving slower? I’ll be in my own head so much that I feel like it’ll effect my work performance out of nowhere. I’ll be at a good pace at the start of the day then suddenly my whole energy and thought process will just shift downwards. I thought it was burnout but idk anymore.

Anyone that’s been in this situation how did you combat that shit?