Jesus' statement is a call both to Mary and Martha, not just to Martha. Martha's activity was good, Mary's was better, but neither was good enough. Both needed to move into the union and harmony of the two, which is the contemplative dimension of the gospel. Through contemplative prayer we come under the influence of the Spirit both in prayer and action. Then action is truly prayer.
Prayer is relationship, and hence capable of almost infinite growth.
Relationship can go on growing forever, especially relationship with the infinite God. Prayer is the relationship in which purity of heart, reached through the unloading of the unconscious and the dismantling of the false-self system, opens us to the will of God in everything and enables us to respond out of divine love to the events of everyday life. She was serving the Lord to please herself, not with purity of heart, which seeks to please God and to do what divine love would do in each situation. Her agitation pointed to the fact that one of her emotional programs for happiness had been frustrated. There was nothing wrong with her activity, but to be agitated or upset indicated that she was under the influence of the false-self and withdrawn from the purity of divine inspiration.