Moroni 2:2

And he called them by name, saying: Ye shall call on the Father in my name, in mighty prayer; and after ye have done this ye shall have power that to him upon whom ye shall lay your hands, ye shall give the Holy Ghost; and in my name shall ye give it, for thus do mine apostles.

When Christ ordained his twelve special Nephite disciples, he gave them authority, but he added instructions that to exercise that authority with power, they had to pray.

Authority and power are  not synonymous. Authority is the right to do something; power is the ability to do it. We get our abilities from God. The enabling power of God is called grace. We must pray for grace, as we would for any worthwhile gift. God gives marvelous gifts, but only when we ask.

Neither can the asking be casual or occasional. The disciples, with all their authority and witness,  still needed to exercise "mighty prayer." Mighty prayer is the kind of prayer we offer when we know we are totally dependent on God's grace and no other help is available. In a mighty prayer we say, "Lord, it is you or nothing. I have nowhere else to go and no one else to lean on. Whatever you do is good, and so, give me whatever is good. Just don't  leave me alone."

Ether 1:34

And the brother of Jared being a large and mighty man, and a man highly favored of the Lord, Jared, his brother, said unto him: Cry unto the Lord, that he will not confound us that we may not understand our words.

In this and the next five verses, the brother of Jared "cries unto the Lord" for compassion and help. The difference between just praying, which most of us do on a regular basis, and crying, which yields miraculous results, is in the intent and intensity of the experience. When we are desperate, when we have exhausted our mortal means and cannot take another step, we cry unto God.

Most days, however, we are not desperate, or at least we do not recognize how desperate we should be. Most of the time we think we have life under control. We have our routines, we work, we solve little problems, and we take our blessings for granted. Only when we are faced with a crisis -- a dying parent, a sick spouse, a rebellious child, loss of a job, or some other disaster -- do we get serious enough about seeking divine help that we finally cry unto the Lord.

I'm sure our Father understands that mortals cannot live 24x7 in utter crisis mode. Nevertheless, if we truly understood the ultimately desperate situation of mortality, we would cry every day unto God. We teeter on the brink of spiritual death every day. We need daily forgiveness in the worst way. We need grace at every step. We need the constant companionship of the Holy Ghost -- constantly.

We cannot manufacture faith or charity or any other spiritual gift. We are totally dependent on Christ for justification, sanctification, redemption and salvation. To think any other way is to be blind to reality. Yet we fumble our way through most days in total denial of our desperation.

But God is patient and kind, and he lets us have our delusion of self-sufficiency. Only occasionally does he drop a hint that we are living really on thin ice. We face an unexpected setback or a crisis and, if we are wise, we cry unto him, and in that moment we finally get out of his way so he can go to work in our lives.

3 Nephi 27:1

And it came to pass that as the disciples of Jesus were journeying and were preaching the things which they had both heard and seen, and were baptizing in the name of Jesus, it came to pass that the disciples were gathered together and were united in mighty prayer and fasting.

Mighty prayer is not just plain old prayer. We do not dash off a mighty prayer for two minutes before we jump into bed at the end of a long day. A mighty prayer is a prayer of power, offered with sincerity and genuine desire, born of a heart felt need, and accompanied by total humility. A mighty prayer recognizes that no other source but God can supply the relief we seek. It has full confidence that the Lord can and will answer, but it also asks according to his will, guided by the Holy Ghost. A mighty prayer does not have to be long, but it must to sufficient to allow one to pour out his heart and say all that needs to be said, followed by time to listen and ponder. The Lord gives us hard problems and painful afflictions so we can learn mighty prayer.