Notice the differences in this example.

When we grasp onto the content of the thoughts, we can be convinced of their truth and solidity.

Our emotional reaction intensifies.

When we first observe thoughts with non-judgment and curiosity (like clouds passing in the sky, or like leaves floating down a stream), we begin to notice the tendency of the mind to generate thoughts. We might even begin to notice the quality of the thoughts – are they helpful or not?

From this perspective, we can detach a bit from our own reactivity, gain some distance, and become better able to discern the importance, truthfulness or relevance of our thoughts. By mean of this type of curious observation, we can be less caught up in unhealthy thought patters and act from a position of greater balance. This curious, open and non-reactive noticing is what we practice in mindfulness of thoughts.