We, God’s immortal children, forgot our natural state of perfect immortality, and began to desire only mortal, delusive perfection. With the "delusion of ego" comes the added "delusion of happiness" which is short lived and always ends in suffering due to the insatiable nature of ego's attachment to desire. It can never get enough! This is the duality of the physical world.
"Ego consciousness" comes with an unwelcome guest - "duality". Duality dictates that after every positive ego experience there must eventually come its negative ego experience twin - suffering. The only way to avoid suffering is to transcend ego consciousness. One of the most effective ways to accomplish this is through the scientific techniques of yoga meditation.