Yes. I have had a severe panic disorder that lasted 2 years (11 years ago) of 24/7 panic, even in sleep. Then I turned schizophrenic and heard between 1-1000s of voices, which lasted a year (4 years ago), and then have had a very difficult life of many "mental breakdowns" where I thought I would "lose my mind." I am having one now, to be frank.
I backed myself out of the panic and schizo by learning to control my thoughts. I did post a short explanation of what I did, so if interested, checking my posts will show that. I had 100% cure of both panic and schizo with no meds or treatments, past a few supplements I took as needed. No relapses either. It was very hard on a minute-to-minute basis, but proved effective with much practice and time.
The other times I feel like I am going mad, controlling thoughts can help, but I am less inclined to bother because if I am angry because Drs destroyed my body and I am in severe pain (like I am now), I am less interested in taking personal responsibility to change MYSELF and my thinking and feelings I am having about my situation that THEY caused me, even if it would help me feel better, see? I am not trying to be a "brat" about it, I am just feeling it is over-the-top to expect me to think differently about severe disability (for example) and try to override the reality with different thinking. But I AM attempting to do that on/off now, to maybe save my life.
I KNOW it IS possible to get control and cure mental issues. I have done it in the past where all hope seemed lost. My aunt has been institutionalized for schizophrenia for the last 45 years. I did have it come on for me, but I began trying to cure it right when it cropped up the same I did the panic, and it worked. Right now, I am toying with the idea I can use the same techniques to CURE physical issues (mind over matter, per se) but am feeling a bit doubtful and impatient with the thought of trying.
But I want to say that I KNOW mental issues CAN be controlled and cured, from experience, with work on your part. Outside help is not necessary, and I personally did not take that route of therapy and medications because of bad past experiences.
You can contact me if you want any help/info with any of the techniques I employed. I have read 20 yrs worth of therapy books as well, but really find those methods to not work for me in practice. Too complicated and formal and not good to use in a pinch of a real emergency where you can't even think straight.
Edit to add: With my schizo, I had the voices, and they did appear to come from all over my body (so a voice would come from the stomach, etc...), and I had a lot of painful things happen (like feeling my intestines were being squeezed, getting zapped, sensations of getting burned or cold, etc...) No visual hallucinations, though.