Sehaj is the ultimate positive state of Mind in all Perfection, where GOD abides in humans. The aim of Sikh Teachings in nut shell is to attain to this State of Mind in union with Him. Sri Guru Arjan Dev in Rag Gauri, Astpadi 4, at page 237 Sri Guru Granth Sahib states -
"Which is the place where there is ever consistency, and which that WORD (God's Light) is that cleans our evil mind? (1 Pause).
The state of Contemplation of the Lord in His Praises, is the Highest state of Mind of Sehaj, the Essence of Worship, which takes man to Highest Eternal Wisdom, Joy and Eternal Truth. In that Realm of the Holy One, one utters and relishes the Praises of the Lord, and ever abides in the Domain of Fearlessness. (6)
There is no fear there, no doubts, and no sorrow of any kind. One is then redeemed from the cycle of repeated births and deaths. There, one is in the state of Eternal Joy, which springs from the Celestial Melodies. There, the devotees lean on nothing else but on the Lord's Praises. (7) "
(For detailed description of Sehaj, please refer to the article "Sehaj - The Eternal Peace of Mind")