Although not a very old man, I have yet lived a great deal in my life, and I have known sorrow too bitter and joy too keen to allow me to become either cast down or elated for more than a very brief period over any success or defeat.
It's always necessary to know when a stage of one's life has ended. If you stubbornly cling to it after the need has passed, you lose the joy and meaning of the rest. And you risk being shaken to your senses by God.
When firmly planted, your testimony of the gospel, of the Savior, and of our Heavenly Father will influence all that you do throughout your life. It will help to determine how you spend your time and with whom you choose to associate. It will affect the way you treat your family, how you interact with others. It will bring love, peace, and joy into your life.
You know that kind of quiver that trembles around through you when you are seeing something so strange and enchanting and wonderful that it is just a fearful joy to be alive and look at it; and you know how you gaze, and your lips turn dry and your breath comes short, but you wouldn't be anywhere but there, not for the world.
Whoever possesses abundant joy must be a good man: but he is probably not the cleverest man, although he achieves exactly what it is that the cleverest man strives with all his cleverness to achieve.