Karma is the law of the cycle of cause and effect. Every positive or negative volitional act—mental, vocal, or physical—will produce its commensurate effects in the form of pleasant or painful results. That is the ineluctable law of life of all ordinary beings and the conventional world.
The past positive or negative deeds of beings determine their future happiness or painful experiences. All the experiences of our lives are mere responses and reactions to what we have been registering in our mind-stream, thereby planting habitual karmic seeds in the universal ground, the unconsciousness state, of our mind. Every happening of our life is the maturation of those karmic seeds. Seeds of positive deeds, such as the thoughts, words, and physical actions of love and wisdom will produce peaceful, happy, and enlightening results. Dislike, anger, and attachment bring us only pain and suffering. Until the attainment of buddhahood, which transcends the karmic cycle, we will be enjoying continuously the effects of the past karmas, and in every moment we are creating many new karmas. Such karma can be created and experienced collectively by many beings together or individually. Karmic results are not about rewards or punishments that are carried out by some external forces or agents, but they are the effects of the actions and reactions of our own deeds that are returning to us.
Therefore, if one has lived with positive deeds, then because of the force of that karmic law, one will enjoy a peaceful and joyful life now and in future lives. Especially, if one has realized high spiritual attainments, one will not only be enjoying a peaceful and joyful life but will also become a great source of peace and joy for many.