What does that mean? Watchman Nee said it best that all too often we seek to be in the presence of God and arrive there in prayer. But when the prayer is over somehow they are no longer in His presence (The Breaking of The Outer Man and Release of The Spirit). So how do I maintain the "spiritual walk" apart from the closet? This is done by walking in obedience to the Father after we "come down off the mountain." It is in the valley the Lord wants us to walk in what he has given us on the mount. The truest measure that my "mountain top experience" was spiritual is my carrying it out in the valley. I am not saying that there will not be difficulty. However in the face of difficulty we have a zeal, an intention, a purpose to do that which the Father has commanded.
Walking in the spirit is not a mystery to those who seek His face. However apart from clear biblical teaching is can be very misunderstood.
There are some that believe that walking in the spirit is hearing an inward voice and being led by that voice (only). Others believe that it is reading the scripture following it apart from any impressions (only). I believe they are both right and wrong. It is both.
Walking in the spirit is an absolute necessity. The scripture (Romans 8:1) says that if one does not walk in the spirit they will be condemned. So using God revealed will (the scripture) I walk in obedience to Him, in communion with Him. However when necessary God, by the Spirit, leads me to do some particular thing that in no way conflicts with His revealed will. For instance in the course of my day the Spirit may lead me to put a gospel tract in my pocket. The Spirit then compels me to give the tract to someone. In this instance I am walking in the Spirit just as much as one who does not steal or commits adultery.
As my senses are excersized (by reason of use) I will be able to discern between good and evil.