Most people have a hard time giving because they have misunderstood the results of previous attempts. They remember being disappointed and victimized . They don't trust giving because they think they have given before and have been burned. But they have not.
What they have called giving was actually a form of trading. Trading is not giving. Trading is an act that focuses on what the return will be. True giving does not focus on the return. It focuses on the giving. The giver gives without conditions, and then moves mental energy to the next person to give to, and never looks back.
Accomplished givers become filled with self-respect. Often they are formerly takers who have reinvented themselves. They are not giving in order to get happiness in return. The happiness is already there. It lives inside the act of giving.