D&C 98

To the saints in Missouri, the Lord teaches the doctrine -

"...I have decreed in my heart, saith the Lord, that I will prove you in all things, whether you will abide in my covenant, even unto death, that you may be found worthy.
15 For if ye will not abide in my covenant ye are not worthy of me."  (Doctrine and Covenants 98:14–15)

It becomes that simple, will we keep our covenants unto deaths?  If we do, we are chosen and worthy for eternal life.