Well, this is the thing, we don't choose our thoughts. They just appear. See for yourself. Just sit and do nothing. Soon, thoughts will start coming into your mind. Why those particular thoughts?

To consciously choose your thoughts would mean knowing what your thoughts are going to be before you've thought them, which is impossible.

So then, if you're not your thoughts, what are you? Exactly! One of the paths to enlightenment is removing all the things which are not really you until finally there is nothing left.