D&C 120

While incarcerated in Liberty Jail, the Prophet Joseph Smith wrote a letter to the saints.  As he did, he was overcome by the Spirit writing -

"O GOD, where art thou? And where is the pavilion that covereth thy hiding place?
2  How long shall thy hand be stayed, and thine eye, yea thy pure eye, behold from the eternal heavens the wrongs of thy people and of thy servants, and thine ear be penetrated with their cries?
3  Yea, O Lord, how long shall they suffer these wrongs and unlawful oppressions, before thine heart shall be softened toward them, and thy bowels be moved with compassion toward them?"  (Doctrine and Covenants | Section 121:1 - 3)

Even pleading -

"Remember thy suffering saints, O our God..."  (Doctrine and Covenants | Section 121:6)

The Lord then answered this prayer with an eternal or His perspective -

"My son, peace be unto thy soul; thine adversity and thine afflictions shall be but a small moment;
8 And then, if thou endure it well, God shall exalt thee on high..."  (Doctrine and Covenants | Section 121:7 - 8)

And then as the Prophet continues to write the letter, the Savior teaches this eternal perspective.  As He does, you can sense the impact on the Prophet as he concludes His letter with -

"Therefore, dearly beloved brethren, let us cheerfully do all things that lie in our power; and then may we stand still, with the utmost assurance, to see the salvation of God, and for his arm to be revealed."  (Doctrine and Covenants | Section 123:17)

This is what happens to us when we have a "high mountain" experience.  When we look at things for the Lord's or and eternal perspective.