A "normal" person can become psychotic under certain conditions such as sleep deprivation or taking narcotics. However, many newly, correctly diagnosed people with schizophrenia, as a form of denial, will decide that their problem was just due to the drugs they took or to lack of sleep.
When it is due to the brain being wired incorrectly (such as in schizophrenia), psychosis can be a lifelong condition. Thus, at no point could you accurately say, "I'm past my mental illness and from now on I will always be totally normal." Constant vigilance is required because even without repeat hospitalizations, lower level problems could recur.
Probably due to my paranoid condition, I find it hard to trust anyone or anything. This interferes with nearly all of the relationships in my life. My medication and therapy help me not go into an acute mode of paranoid psychosis, yet I constantly have a little bit of it on a more tolerable volume level.
Some fear is a life preserver and will make a person prudently cautious. However, some fear is irrational and can ruin a person's life. Distinguishing which type of fear you have, (e.g., useful fear or irrational fear) can be difficult.
When paranoid, you might feel that a possible mishap lurks around every corner. And when something on occasion does go wrong, it only adds fuel to your belief of constant danger.
Other people can't always detect one's paranoia and fear, since sometimes there are no external signs. Paranoia usually isn't anyone's fault, and is caused by the way in which someone's brain misdeveloped. It is not a sign that the bearer is weak or unintelligent.
The part of the brain responsible for paranoia is a primitive area left over from prehistoric reptilian ancestors. The part of the brain responsible for higher functions, the cerebral cortex, is often left perfectly intact and functional. Thus, someone could have a paranoid disorder and could be normal or even exceptional otherwise.
When paranoia takes over the mind, it is as though the mind has been hijacked. It blocks proper usage of the higher functions of the mind that could otherwise more effectively deal with a real life challenge.
When I attempted work at various jobs, sometimes the work attempt was successful, and I stayed with some jobs for a year or so. In other instances, I was unaware of it, but paranoid perceptions made me feel threatened by the work environment. Some jobs were quite unbearable because of this, and I resigned from some jobs without notice. In the jobs where I felt closer to being comfortable, it was because I had a rapport with coworkers and supervisors.
I can recall in my teen years and in fact back to early childhood, there were a lot of environments in which I didn't feel safe--particularly in the public school systems. Other students seemed big, mean and dangerous. They talked loud, laughed meanly and spat "loogies" on the pavement. Some of them were assaultive.
In the development of the schizophrenic mind, something may go wrong very early in life in which the brain doesn't grasp how to defend oneself and feel safe.