Not every hard job is toxic. There's a difference between a demanding stretch and an environment that wears you down systematically. In the latter, criticism becomes personal, boundaries don't exist, recognition is rare and uncertainty is constant. Little by little you start doubting your own abilities, even if you were doing just fine somewhere else not long ago.
Mobbing — systematic psychological harassment at work — is a particularly damaging form of toxicity. It can take the shape of exclusion, undermining, constant belittling or excessive control. Because it rarely happens openly, you often wonder whether you're overreacting or "imagining it." That very doubt is part of the mechanism that keeps you trapped.
The body usually understands first: disrupted sleep, headaches, irritability, a dread that starts on Sunday evening. It's important not to read these signs as personal failure. More often they show that a healthy system is reacting reasonably to an unhealthy environment.
The question isn't always "should I leave?" It's also "how do I protect myself while I'm here, and how do I get my strength back?" In therapy you can clarify what belongs to you and what belongs to the workplace, rebuild boundaries and self-esteem, and decide with a clear mind. See how working on a toxic work environment can help.