Possible reasons for negative thoughts if you are a survivor of abuse, combat or trauma experiences or just experienced hurtful situations.
Negative thinking generally can be a result of your daily life. Events in your daily life can remind your subconscious of past traumatic situations.
Elements of Memory
Route #1 is when negative thoughts surface as the result of a current situation stimulating a visual memory of a previous event. The memory would then causes an associated core belief to surface into and then be released from your subconscious mind into your conscious mind. You are not always aware that a core belief has surfaced or why. Then the surfacing core belief directly influences the content of your thinking unknowingly to you. A negative core belief would generate negative thinking.
Both routes heavily influence you and run quietly in the running in the background. Each route causes you to think in negative ways and as a result you think you are going crazy or just simply hate yourself. You know nothing going on or happening in the moment to cause you to think so the negative about yourself, so you must be crazy. But be assured that you are not crazy. Nothing happens in your mind unless it has be written as a result of your life experiences
The positive thing is once you learn and understand the reasons why you are thinking negatively today, you won't feel like you are crazy anymore.
Another positive thing is that it is possible to make a shift from negative thinking to positive thinking. It is also possible to neutralizing the influence negative thoughts have on you, so the thoughts no longer dis-empower you or causes self-sabotaging thinking.
Shifting negative thoughts can be as easy as changing your negative core beliefs. Once your core beliefs are changed to positive then the content your mind generates to your thinking process will be positive.