If we allow it to happen, we spend the vast majority of our physical existence creating endless thoughts about what we think is us derived from the past and our imagination of the future and then acting on those thoughts and seeing ourselves as those thoughts.
Our mind is a part of us and the thoughts that the mind creates are a part of us, but they are not us. We can choose to simply observe them without judging.
Once the mind controls rather than us controlling it, we then become our thoughts.
We are not our thoughts if we choose to be conscious.