i do agree with you are the only person that can control *your* thoughts, we must also consider the thoughts which are not *ours* and have a origin which me may not know and be placed into our mind by a entity, these thoughts put in our minds by entities such as things like spirit guides as a example are not ours ( same goes for any other entities which are around us which can access our minds/thoughts or have the know how to control what enters our minds/thoughts) and we don't have the control of the thought like we would if we were not effected by any internal or external thing( cant really think of a good example or term for this other than our base line thoughts but even still its not a good example/term), this makes it tricky and somewhat misleading and can cause a few more negative thoughts when a person is unable to control thoughts and that leads to questioning and self doubting and dispair which just creates more negative stuff inside ones mind
if i have missed anything please let me know