Rest happens only when someone's full weight is surrendered. Laying your head on someone's shoulder isn't comfortable if you're using half your energy to hold up your own head in effort to conceal your full weight from the other. Rest then is heavy. It's a place where our heaviness is accepted, received, and held, and without fear that the one holding is insecure or unstable, receiving our weight with resentment or as a burden (be it a couch, a table, or the relational presence of another person). It's only then that the lightness of rest can be felt.