In order to hold and bear the acute experience of vulnerability, you need an appropriate container. The practice of consciously putting up boundaries is part of creating a container. Creating a boundary can mean something as simple as maintaining a physical distance between you and another person, setting personal limits, being able to say "no" appropriately, and understanding whom you're willing to let into your intimate inner circle. Another form of container is a relationship of trust—certain friendships, your teacher, or a practice community can help you find safe spaces in which to open.
Eventually, when you are living in that center, you may start to experiment. How open can I be in this situation? What do I do when I feel overwhelmed by others' energies? A mature practitioner knows when to put up an energetic barrier or shield, and a kind of automatic protective energy system comes into play when needed. He or she also knows when a barrier or shield is just a device that's blocking intimacy.
When you allow yourself to consciously enter the state of vulnerability, you find that at its heart is peace. The peace that comes from standing poised in the aching heart of life. The peace that is your true protection, your invulnerable core." Sally Kempton.