I will teach you the anxiety that comes from clinging and the peace that comes from release.
So, how does clinging lead to anxiety? For someone who hasn’t been taught the dhamma, they believe that their body is their true self. But inevitably the body changes and decays, and this brings heartbreak and misery. Or they believe that their sensations, thoughts, or even consciousness itself is their true self. But like the body, these things inevitably change and decay, and this brings heartbreak and misery.
So how can one find the peace that comes from release? A dedicated spiritual seeker looks carefully at the body and realizes, “This is not my true self.” For them is the peace, even when their body changes and decays. Likewise they look carefully at their sensations, thoughts, and even consciousness itself and realize, “None of these is my true self.” And when these things, like the body, inevitably change and decay, there is only peace.
-Upādāparitassanā Sutta SN 22.8 (S iii 18)