Sometimes we resist. Maybe we come from a family which didn't accept gifts well; we don't feel worthy; we believe that our only worth and identity is in what we give others; we believe our only worth and identity is in our hard work and self-sacrifice; we secretly believe we need to punish ourselves for past deeds or to keep ourselves pure or motivated; we are out of the habit; we believe there is too much suffering in the world to take any joy for ourselves; we don't want to feel dependent or obligated; we believe our worth is in our self-sufficiency. All of these beliefs blind and bind us.
How do you feel when you offer a generous gift - one you genuinely want to give and know is needed - and someone rejects it for unhealthy reasons? Don't be that person. Practice accepting gifts.