Eternal Life is something that we as Latter Day Saints are taught to prepare for now.
The Lord is very specific when He teaches exactly how that will be achieved. He answered that question Himself in the preface of the Doctrine and Covenants, or Section 1.
A "preface" typically outlines what the rest of the book is about, and in His perfect way the Lord does exactly that. He outlines beautifully who the book is for, what is contained in the book itself, and the reason that He is giving the information in the book to His people.
Who is the book for?
Clearly the book is for all people everywhere. It is for everyone.
What is the reason for the book?
Furthermore, it is explained that there are several reasons why the book is to be compiled.
Among them is simply that of preparation, for He is coming again.
"Prepare ye, prepare ye for that which is to come, for the Lord is nigh;"
Part of that preparation comes about by listening to His appointed servants, mainly His prophets and apostles. This may be one of the first and most important steps in living the kind of life that is needed to prepare for "eternal life."
Another reason the Lord needed to reiterate His instructions to His people is related by this verses:
15 For they have strayed from mine ordinances, and have broken mine everlasting covenant;
16 They seek not the Lord to establish his righteousness, but every man walketh in his own way, and after the image of his own god, whose image is in the likeness of the world, and whose substance is that of an idol, which waxeth old and shall perish in Babylon, even Babylon the great, which shall fall.
I personally think that this is precisely the description of the world we live in today or modern day Babylon, don't you?
Now for the exact reason he decided to give us the blessing of this added book of scripture...
"Wherefore, I the Lord, knowing the calamity which should come upon the inhabitants of the earth, called upon my servant Joseph Smith, Jun., and spake unto him from heaven, and gave him commandments;"
Calamities are surrounding us, but the biggest one would be that of forgetting the first commandment, to love the Lord thy God and to remember the covenants He has made with His children.
The biggest reason for this added scripture is so that weak things will break down the mighty and strong, faith will increase, every man might speak in His name, his "everlasting covenant" might be established, and the "fulness of his gospel" might be exclaimed.
So what exactly is His "everlasting covenant?"
It is, simply stated, "I will be your God, and you will be my people".
This is what it will take to have eternal life...this is the main condition set by the Lord himself. But what does this really mean though?
It means that you will do everything he says, be everything he requires and love Him unconditionally.
How can you do that?
By listening to His appointed servants, mainly His prophets and apostles. It is really one Eternal Round!
Now what is the second part all about, the "fulness of His Gospel"?
It is referring to the Everlasting Gospel of Jesus Christ as preached to the earth from the beginning of time.
It involves the restoration of His "ordinances" that are required for admittance into His presence.
The Doctrine and Covenants is an instruction book of these required ordinances, the first one being Baptism and receiving the Gift of The Holy Ghost. He instructs that repentance and living His commandments (one of them being baptism), will give one the light from the Spirit which is available to "all flesh". Upon reception of the Holy Ghost, he will instruct you by his spirit all things which you must do.
Finally, he gives added instruction and testimony:
37 Search these commandments, for they are true and faithful, and the prophecies and promises which are in them shall all be fulfilled.
38 What I the Lord have spoken, I have spoken, and I excuse not myself; and though the heavens and the earth pass away, my word shall not pass away, but shall all be fulfilled, whether by mine own voice or by the voice of my servants, it is the same.
In perfect fairness, the same thing is required of all men everywhere, and he "excuses even not himself" from this path or way to return back to be in the presence of the Father. The path is perfect, fixed, set, and immovable.
So if you think that by "grace" you may be the exception to the rule, perhaps a study of law must be further discussed.
The Doctrine and Covenants outlines beautifully what is required to return to our Father in Heaven. Now all we have to do is "learn and do" or "search and apply" that which is written.