Nobody has any control over their thoughts, you don’t know what you are going to think of next, they bubble up into your awareness fully formed and instantly cognisable.
Some thoughts you might like, some thoughts not so much.
Many thoughts are the result of previously accepted opinions, attitudes and life experiences that have impressed themselves into your awareness of self, they can frequently be conflicted and confusing which leads to mental illness, particularly when the bulk of those thoughts are all about the expectations that others may have of you.
Agreeable and conscientious people tend to be the one’s with mental illnesses, they’ve tried their best to please the important people in their lives such as family, friends and employers often putting their needs above their own and have hit upon an internal conflict in their values/expectations where the rational mind wants to go one way and the subconscious/irrational mind wants to go another way entirely.
This can result in strange behaviours and internal ideas/attitudes that others might judge to be mental health issues. At some stage in their lives everyone will experience a mental health crisis/issue or live with someone that is going through one. That’s a fact.
So in answer to your question:
‘What is it like to not have control of your thoughts and emotions, as in mental illness?’
If you hang around long enough you will soon find out…