I agree with Dr. Beck’s characterization regarding “cognitive distortions” or “negative automatic thoughts,” because there is overwhelming evidence demonstrating that rumination (i.e., constantly worrying, being preoccupied with depression, being anxious about the future, etc.) is a transdiagnostic risk factor for mental illness, and that mindfulness practices can significantly reduce rumination. So, if mindfulness practices are incorporated into CBT, this mode of therapy could be very effective. These practices are also capable of changing areas of the brain that are associated with stress/anxiety. See for example the following references:
Kaplan, D. M., et al. (2018). Maladaptive repetitive thought as a transdiagnostic phenomenon and treatment target: An integrative review. Journal of clinical psychology, 74(7), 1126-1136.
Sevinc, G., et al. (2020). Hippocampal circuits underlie improvements in self‐reported anxiety following mindfulness training. Brain and behavior, 10(9), e01766.
Keng SL, Smoski MJ, Robins CJ (August 2011). "Effects of mindfulness on psychological health: a review of empirical studies". Clinical Psychology Review. 31 (6): 1041–56.
Tomlinson, E. R., Yousaf, O., Vittersø, A. D., & Jones, L. (2018). Dispositional mindfulness and psychological health: a systematic review. Mindfulness, 9(1), 23-43.
Tang, Y. Y., et al. (2015). The neuroscience of mindfulness meditation. Nature Reviews Neuroscience, 16(4), 213-225.
Querstret, D., & Cropley, M. (2013). Assessing treatments used to reduce rumination and/or worry: A systematic review. Clinical Psychology Review, 33, 996-1009.
McLaughlin, K. A., & Nolen-Hoeksema, S. (2011). Rumination as a transdiagnostic factor in depression and anxiety. Behavior Research and Therapy, 49, 186-193.