When many people first discover the Jesus Prayer and its spirituality one of the first things that stands out to them are the physical methods or techniques that are frequently attached to the prayer. Controlled breathing, certain postures, "naval gazing," prostrations, etc., etc., etc. are all mentioned by the Fathers who have written on the Jesus Prayer.
There are several things we must know about this physical techniques before we engage in them. First, they are not essential to the Jesus Prayer, but are merely aids to concentration. As such it is not necessary to use them. The essential thing, as St. Theophan the Recluse says, is to stand before God with the mind in the heart.
Secondly, the Fathers all say that the use of these physical techniques can be dangerous without the guidance of a spiritual father/director (geron or staretz). St. Ignatius Brianchaninov said that these methods can lead (and have led) to physical damage of one's lungs if not performed properly, and St. Theophan the Recluse warns us that the use of such methods without an experienced guide can lead to spiritual delusion/illusion and even a constant state of lust. I've heard of at least two recent instances where folks went insane because they were either disobedient to their spiritual guide when it came to their prayer rule, or they attempted to engage in these methods without the aid of a guide.
So in the absence of a spiritual guide, what are we to do? How can we practice the Jesus Prayer and attain to at least a small amount of concentration on God in our heart? It is quite simple. St. Ignatius Brianchaninov provides us with the technique, and St. Theophan the Recluse with the proper attitude. St. Ignatius says, "The mechanical method... is fully replaced by an unhurried repetition of the prayer, a brief pause after each prayer, quiet and steady breathing and enclosing the mind in the words of the prayer." The "quiet and steady breathing" that St. Ignatius mentions is not the same as the breathing techniques mentioned by Sts. John Climacus, Symeon the New Theologian, or Kallistos and Ignatios Xanthopoulos. Rather this is a deep and steady breathing from the diaphragm, often suggested by doctors for relaxation. Truthfully this method of breathing is the way we ought to be breathing to begin with. A psychology professor of mine once spoke of how many people who came into his clinic suffering from depression and anxiety were cured simply by learning how to breath properly. When singers and musicians are taught to breath, they are always told to breath from the diaphragm, not the lungs. This not only puts more power behind one's breath, but also relaxes the body in the process and calms the mind. Obviously this relaxation of the body and calmness of mind is something that we need when praying the Jesus Prayer or any other prayer.
St. Theophan the Recluse then tells us what our attitude ought to be in prayer. "The work of God is simple: it is prayer - children talking to their Father, without any subtleties." When we approach God in the quietness of our hearts we have to be aware that He is, well, God. He knows us better than we know ourselves. He knows our inner-most hearts, our thoughts, our secrets, what we are proud of and what we are ashamed of. There is no need for subtleties before God. The story of the Publican and the Pharisee in Luke's Gospel illustrates exactly what is meant by subtleties. The Pharisees was too caught up in his own human accomplishments - his fasting, extensive prayers, service to the poor, etc. - to see himself as God sees him. But the Publican simply approached God in humility of heart, recognizing his own sinfulness, his own state before God, and asked for mercy.
Of course, we can talk to God about other things in our lives apart from begging for His mercy. I have a friend in college who's relationship with God was very honest and open. He would go to Eucharistic Adoration and just unload all his troubles and concerns on the Lord, even if he was angry about it. He'd also be the first to shout for joy before the Lord and sing His praises. Children talk to their parents when something is going on with them. They do not mince words or try to cover over the real problem. Their parents have known them since before their births while they were still growing in the womb. In many cases parents know their children better than the children know themselves. So we need to approach God in this same childlike way. Jesus, after all, taught us to call God our "Abba," which does not carry the authoritative connotations of "Father," but the loving connotations of "Daddy" or as we say in my family "Pops."
So when you pray the Jesus Prayer (or any other prayer), don't be concerned about the breathing techniques, prostrations, postures, etc. Simply call out to God in simplicity of heart as a child calls to his Father. Pray slowly and deliberately, not hurriedly. Stay calm, be patient with yourself, and be patient in waiting for God's grace. It may take days, weeks, or years, but in His time God comes to those who call upon Him.