One of the challenges we encounter when we need to let go is fear based. We fear that if we let go, we may never be full again. Since it is fear itself that narrows our ability to receive, it becomes a self fulfilling prophecy. When we experience loss, it is good to honestly acknowledge our emotions about the loss. What we want to avoid is the attachment to the idea that only what we had before will fill us now. That is only a problem if we cling to that faulty belief.
If we use the physical body to teach us, we can observe our breathing. If we choose to exhale, the body will inhale automatically. If we choose to let go and do not attach to fearful beliefs, we will open to bringing in what is good for us. Any good response to life must be practiced. It is the good responses to life that create happiness.