If you find your life of prayer to be always so short, and so easy, and so spiritual, as to be without cost and strain and sweat to you, you may depend upon it, you have not yet begun to pray.
I don't mean that there is too little New Testament language in our prayers; but there is too little both Old and New Testament language meditated on, understood, believed, realised and felt. There is too little Scripture substance, Scripture strength, Scripture depth, and Scripture height, in our prayers.
You do not really care for God's mercy or His comfort either, so long as you live in any sin. And it is well that you do not; for you can have neither. Your peace will be like a river, when you put away your sin; but not one word of true peace, not one drop of true comfort, can you have till then.
No man living in any known sin is ever comforted of God. The Holy Ghost never yet spake one word of all His abounding consolations to any man so long as he lived in any actual sin, or in any neglect of known duty.
Admit sin, and you banish prayer. But, on the other hand, entertain, and encourage, and practice prayer, and sin will sooner or later flee before it.