Action is the body of karma and continues the flow of karma. All actions have causes, and all actions have effects.
I have often said that it is a person's motivation alone that creates karma, rather than their physical actions; thus good intentions are rewarded, even if they sometimes fail to produce the desired result. Yet this is not strictly true, for all actions have an effect in accordance with their causes, regardless of whether those causes are mental or physical.
Even so, it is by far the motivation that brings about the greater consequence. Take the case of an ordinary thoughtless person giving a thousand dollars of their own hard earned money to help a poor man. No doubt there will be an effect here, perhaps even a beneficial effect, but the greatest consequence by far issues from the (impure) motivation behind the action of giving. Ego-based motivations always result in further egotism and destruction, whereas a pure motivation is an eternal well-spring of glorious wisdom. Nothing but good can arise from a pure motivation.
Actions may indeed appear helpful, and the poor may become healthy. However, healthy bodies and happy minds are not reliable indicators of healthy spirits. The poor man's new found wealth may give him the financial space to develop his mind - then well and good - but it is no thanks to the person who gave him money. For it was their intention only to be rid of their guilt, and to experience their warm glow of satisfaction. Any benefit that should come out of such a situation is purely by chance, and is far outweighed by the deleterious effects of a selfish motivation.