Joy or Bliss, arises from peace, equanimity, stability, detachment, renunciation, absence of desires, contentment, devotion, love, and liberation. Life is full of suffering. Yet for those who are caught in the phenomenal world, it is possible to experience eternal bliss or joy.
Joy is a state of freedom. From freedom comes supreme bliss. Hence the best means to experience joy is being liberated. In their ordinary consciousness human beings are incapable of experiencing pure joy because of the interference of the mind and the senses and the attachment of the ego with the sense objects. From the activity of the senses arises attachment and from attachment comes anger and from anger comes delusion and from delusion suffering, which is opposite of joy.
The purpose of religious and spiritual activity is to turn the mind away from the sensory objects and inwards so that both the mind and the ego can be dissolved in an endless state of joy or bliss. Each religion attempts to address it in its own way by suggesting distinct solutions. Whatever may the means they prescribe, the goal of all these religions is always the same, release from the cycle of births and deaths, disease, attachment and suffering.
Pure bliss is a state of mind, you can decide to be joyful, irrespective of your circumstances. The difference between happiness and joy is that your happiness is determined by your senses, what you feel, smell, taste and see. Joy or Bliss is a way of living, it is a way of enduring all suffering with the knowledge that through each bad experience you grow as a person and your mind is moving closer to a state of complete and pure bliss.