Underbelly is term used to describe the side which is not normally seen. Figuratively it means a vulnerable or weak part, similar to the term, Achilles' heel. What is the soft underbelly of where you are at this moment? If you stop and breathe, what is the feeling you might not want anyone else to know about? Can you, at least let yourself know?  What is your deepest longing?  Can you hold yourself with compassion, here? So much of our day to day is blind to our own soft underbelly.  Knowing our vulnerabilities is where our true strength lies.  The work of Core Energetics is often about being able to stand in our naked (figuratively) vulnerability, as a means to deepening our connection to self, Spirit, and others.  There in the underbelly lies our deepest truth, our connection to the Core.  Blessings to you.