JC Ryle preached several wonderful sermons on prayer.
Here is some of his wisdom.
There are others of the Lord’s people who seem to be always advancing. They grow like grass after rain; they increase like Israel in Egypt; they press on like Gideon, though sometimes faint, yet always pursuing. They are ever adding grace to grace, and faith to faith, and strength to strength. Every time you meet them their hearts seems larger, and their spiritual stature taller and stronger. They are not only do well, but they are unwearied in well doing. They attempt great things, and they do great things. When they fail they try again, and when they fall they are soon up again.
It does one good to see, to be with them, and to hear them. When you meet them, you could believe that like Moses, they had just come out from the presence of God. When you part with them you feel warmed by their company, as if your soul had been near a fire. I know such people are rare.
Now how can you account for the difference which I have just described? What is the reason that some believers are so much brighter and holier than others? I believe the difference, in nineteen cases out of twenty, arises from different habits about private prayer. I believe that those who are not eminently holy pray little, and those who are eminently holy pray much.