" Our loving heart, like our physical one, needs an inflow as well as an outflow of lifeblood. And like its physical counterpart, our heart is a muscle, a trust muscle. This trust muscle needs to be used and exercised; if it is injured it will slow down or weaken. We need to take responsibility for this loving function of ourselves and use it. Love concealed or love rejected can both kill us. "

― Henry Cloud , Boundaries: When to Say Yes, How to Say No to Take Control of Your Life