When your mind is pure and uninfluenced by the ego (in other words, no compulsive thoughts, no fear, no worries, no judgment, just gratefulness, neutrality, pure acceptance and non-resistance), joy pervades every waking moment. You don't even have to seek joy. More accurately, you cannot seek joy. How can something be found (which would indicate a source that is external) when it already exists within? You just have to learn to calm your mind and feel the inner stillness and peace. It is neither a complex nor religious concept (though it can be hard to practice constantly). Simply acknowledge each experience, emotion, thought, as they come, and release (ie. let them go with a loving awareness, without dwelling on the cause). When nothing stays and you accept the impermanence of things, how can you suffer? The only state that remains is that of peace.