Here is what Elder L. Tom Perry said.
There are two purposes for life in mortality. The first is that we might gain experiences that we could not obtain in any other way. The second is to obtain tabernacles of flesh and bones. Both of these purposes are vital to the existence of man. We are now being tried and tested to see if we will do all the things the Lord has commanded us to do. These commandments are the principles and ordinances of the gospel, and they constitute the gospel of Jesus Christ. Every principle and ordinance has a bearing upon the whole purpose of our testing, which is to prepare us to return to our Heavenly Father and become more like Him. Elder Bruce R. McConkie has said this about following the straight and narrow path:
“What I think all of us need to do is to determine where we stand in every field of mortal endeavor. Then, based on the general overall concepts that are clear and plain, we make a determination on how we will live in this field or in that field in order to pass the probationary estate in order to succeed in the test of mortality. If we make the right choices, we’ll go on to eternal reward, and if we do not, then we’ll get some lower and lesser place in the kingdoms that are prepared.
“… Everyone in the Church who is on the straight and narrow path, who is striving and struggling and desiring to do what is right, though [he] is far from perfect in this life; if he passes out of this life while he’s on the straight and narrow, he’s going to go on to eternal reward in his Father’s kingdom” (The Probationary Test of Mortality,devotional address, Salt Lake Institute of Religion, Jan. 10, 1982, 8–9).