The three gunas influence everything in accordance with karma. We have a psychological, physiological, emotional disposition that we have developed mechanically through the ages. In each lifetime, we are predisposed egotistically towards one guna. This guna influenced the development of our three brains, and influences our moment to moment perception, digestion, thinking, feeling, etc. Our way of thinking, feeling, and our body (a karmic expression) are sattvic, tamasic, or rajasic. Knowing this disposition can lead us towards balance. Nevertheless: it is egotistical, not a quality of the Being. In this regard, it is similar to our astrological disposition: something mechanical.
“Nothing is easier than self-deceit. For what each man wishes, that he also believes.” —Demosthenes
"Do not worry; cultivate the habit of being happy." —Samael Aun Weor