We experience positive and negative thoughts in our minds. But these positive and negative thoughts do not affect the true nature of the mind, just like good or bad weather does not affect the truth of the sky.
The birth and death of a thought concerns only the thought. It does not concern the mind, the true nature of phenomena. Rain and sunny weather are just ingenious manifestation of various causes and conditions. They do not affect the sky itself.
Therefore, emotions should not be believed to be an absolute truth, and self-awareness is the only way to remove this erroneous view.