Why is receiving so difficult?

Each year during the season of giving, I find it to be so difficult for many of us to be on the receiving end of gifts. Like many of you, I find it much easier to be the nurturer and giver because I feel so wonderfully fulfilled by helping others. But the sneaky other side of that statement is that I often equate receiving with worthiness and I feel greedy if I take too much. So much so that I have seemingly no problem pouring from an empty cup? It just goes to show that many of us have some work to do before we go into potentially stressful holiday dynamics with colleagues and family.