Why we need to have an Intimate Conversation with Christ

The published prayers of saints and spiritual writers have a definite value in the spiritual life – they demonstrate a method and outline for conversation with Our Lord.
But Christ would be sorely disappointed were we to hide behind the words of these prayers. Our Blessed Lord wishes us to talk to Him in our own words and with our own expressions, as awkward and as ungrammatical as they may be.
When the moment for our conversation with Christ arrives, He wants to hear our words and our sentiments. Nothing more is required; nothing less would be satisfactory.
St Teresa comments on this:
With regard to the habit of conversing often with your Divine Spouse, be confident that He will suggest to your heart what to say.
You are not embarrassed when you speak to His creatures, why should words fail you when you wish to speak to your God? Do not believe that will happen to you; for my part, at least, I look on that as impossible if you have acquired the habit of this interior conversation with Our Lord.
The soul can picture itself in the presence of Christ, and accustom itself to becoming enkindled with great love for His sacred humanity and to have Him ever with it and speak with Him, ask Him for the things it has need of, make complaints to Him of its trials, rejoice with Him in its joys and yet never allow its joys to make it forgetful of Him. It has no need to think out set prayers but can use just such words as suit its desires and needs.
St. Teresa make her point deftly: if we can talk to our acquaintances, why can we not talk to Christ?No one requires training in the art of conversation; it is a natural habit acquired early in life. Well enough, then! Let us apply our natural facility for conversation to this colloquy with Christ.
Our Lord has expressed our relationship to Him in quite human terms – “I call you now not servants, but friends”; He expects us to fulfill our part of the relationship in the most common act of friendship, intimate conversation.
(Conversation with Christ: the teaching of St. Teresa of Avila about Personal Prayer )