Our prefrontal cortex (PFC) is our attentional control center. It helps us plan and organize. It is the part of the brain that most separates us from other animals. Bad news, as you age, your prefrontal cortex thins. Good news, if you meditate, you can maintain the thickness of your prefrontal cortex through aging. According to an amazing study by Dr. Sarah Lazar, Harvard, long term meditators in the 40s and 50s had the prefrontal cortex thickness of 20-30 year olds.
Reference: Lazar, S. W., Kerr, C. E., Wasserman, R. H., Gray, J. R., Greve, D. N., Treadway, M. T., McGarvey, M., Quinn, B. T., Dusek, J. A., Benson, H., Rauch, S. L., Moore, C. I., … Fischl, B. (2005). Meditation experience is associated with increased cortical thickness. Neuroreport, 16(17), 1893-7.