You don’t always think what you think that you think. Sometimes it’s actually an emotion and not a thought at all.
When you have a thought in mind, try putting it into words by either explaining it to someone in a conversation or writing it down on paper. Then you will know if you were thinking precisely what you thought you were thinking and, further, if it actually makes some bit of sense.
When you have an emotion in your heart, do the same thing—try putting it into words.
In my own experience, I have had thoughts that I believed to be strong and true, but when I tried to explain them to someone else in a conversation I realized either that my thought was still incomplete and/or tangled, or that there were gaps and inconsistencies in the thought, pointed out to me in conversation.
I have had emotions that I felt deeply and passionately, but when I tried to write them down the passion faded or seemed irrational. This has been especially helpful when I have experienced emotions that can become negative, like sadness or anger.