The spirit world is an active place where growth and progression are possible

https://www.lds.org/manual/teachings-brigham-young/chapter-38?lang=eng 

When you are in the spirit world, everything there will appear as natural as things now do. Spirits will be familiar with spirits in the spirit world—will converse, behold, and exercise every variety of communication with one another as familiarly and naturally as while here in tabernacles. There, as here, all things will be natural, and you will understand them as you now understand natural things. You will there see that those spirits we are speaking of are active; they sleep not. And you will learn that they are striving with all their might—laboring and toiling diligently as any individual would to accomplish an act in this world (Discourses of Brigham Young [DBY[, 380).

Spirits are just as familiar with spirits as bodies are with bodies, though spirits are composed of matter so refined as not to be tangible to this coarser organization. They walk, converse, and have their meetings; and the spirits of good men like Joseph and the Elders, who have left this Church on earth for a season to operate in another sphere, are rallying all their powers and going from place to place preaching the Gospel, and Joseph is directing them, saying, go ahead, my brethren, and if they hedge up your way, walk up and command them to disperse. You have the Priesthood and can disperse them, but if any of them wish to hear the Gospel, preach to them (DBY, 379).

I can say with regard to parting with our friends, and going ourselves, that I have been near enough to understand eternity so that I have had to exercise a great deal more faith to desire to live than I ever exercised in my whole life to live. The brightness and glory of the next apartment is inexpressible. It is not encumbered so that when we advance in years we have to be stubbing along and be careful lest we fall down. We see our youth, even, frequently stubbing their toes and falling down. But yonder, how different! They move with ease and like lightning. If we want to visit Jerusalem, or this, that, or the other place—and I presume we will be permitted if we desire—there we are, looking at its streets. If we want to behold Jerusalem as it was in the days of the Savior; or if we want to see the Garden of Eden as it was when created, there we are, and we see it as it existed spiritually, for it was created first spiritually and then temporally, and spiritually it still remains. And when there we may behold the earth as at the dawn of creation, or we may visit any city we please that exists upon its surface. If we wish to understand how they are living here on these western islands, or in China, we are there; in fact, we are like the light of the morning. … God has revealed some little things, with regard to his movements and power, and the operation and motion of the lightning furnish a fine illustration of the ability of the Almighty (DBY, 380).

When we pass into the spirit world we shall possess a measure of his power. Here, we are continually troubled with ills and ailments of various kinds. In the spirit world we are free from all this and enjoy life, glory, and intelligence; and we have the Father to speak to us, Jesus to speak to us, and angels to speak to us, and we shall enjoy the society of the just and the pure who are in the spirit world until the resurrection (DBY, 380–81).

Suppose, then, that a man is evil in his heart—wholly given up to wickedness, and in that condition dies, his spirit will enter into the spirit world intent upon evil. On the other hand, if we are striving with all the powers and faculties God has given us to improve upon our talents, to prepare ourselves to dwell in eternal life, and the grave receives our bodies while we are thus engaged, with what disposition will our spirits enter their next state? They will be still striving to do the things of God, only in a much greater degree—learning, increasing, growing in grace and in the knowledge of the truth (DBY, 379).

If we are faithful to our religion, when we go into the spirit world, the fallen spirits—Lucifer and the third part of the heavenly hosts that came with him, and the spirits of wicked men who have dwelt upon this earth, the whole of them combined will have no influence over our spirits. Is not that an advantage? Yes. All the rest of the children of men are more or less subject to them, and they are subject to them as they were while here in the flesh (DBY, 379).

Here [the faithful] shall be perplexed and hunted by him; but when we go into the spirit world there we are masters over the power of satan, and he cannot afflict us any more, and this is enough for me to know (Deseret News Weekly [DNW], 1 Oct. 1856, 3).

If a person is baptized for the remission of sins, and dies a short time thereafter, he is not prepared at once to enjoy a fulness of the glory promised to the faithful in the Gospel; for he must be schooled while in the spirit, in the other departments of the house of God, passing on from truth to truth, from intelligence to intelligence, until he is prepared to again receive his body and to enter into the presence of the Father and the Son. We cannot enter into celestial glory in our present state of ignorance and mental darkness (DBY, 378–79).

We have more friends behind the veil than on this side, and they will hail us more joyfully than you were ever welcomed by your parents and friends in this world; and you will rejoice more when you meet them than you ever rejoiced to see a friend in this life; and then we shall go on from step to step, from rejoicing to rejoicing, and from one intelligence and power to another, our happiness becoming more and more exquisite and sensible as we proceed in the words and powers of life (DBY, 379–80).

When we get through this state of being, to the next room, I may call it, we are not going to stop there. We shall still go on, doing all the good we can, administering and officiating for all whom we are permitted to administer and officiate for, and then go on to the next, and to the next, until the Lord shall crown all who have been faithful on this earth, and the work pertaining to the earth is finished, and the Savior, whom we have been helping, has completed his task, and the earth, with all things pertaining to it, is presented to the Father. Then these faithful ones will receive their blessings and crowns, and their inheritances will be set off to them and be given to them, and they will then go on, worlds upon worlds, increasing for ever and ever (DBY, 376).