He "began" to feel this desire as a natural consequence of his own "wholeness." In the Lord's presence we cannot avoid drinking in the charity or pure love which emanates from Him. Christ's most spiritually sensitive apostle described the Lord as love itself. The fact Enos "began to feel a desire for the welfare" of others confirms to us the reality of his association with Christ. Joseph Smith commented on how charity for others is the consequence of knowing God. He put it in these words: "The nearer we get to our heavenly Father, the more we are disposed to look with compassion on perishing souls; we feel that we want to take them upon our shoulders, and cast their sins behind our backs." (TPJS.) Once someone knows they are an heir of salvation, they yearn to see others join them. How can they remain quiet when their family is unredeemed? What of their friends, neighbors, and associates? When Enos turns his attention outward, those he notices first are his brethren, closest in proximity to his own heart. Like concentric circles, with Christ and Enos in the first, now the love spreads out to the next circle of Enos' friends. Eventually the circle will widen to even include Enos' enemies. But first, we learn of his friends: "wherefore, I did pour out my whole soul unto God for them."
The description does not require us to read this as a single outpouring. It is possible Enos did this over a series of days or months. As to pouring out his whole soul, no matter the time frame involved, Enos yearned for his brethren's welfare and made intercession for them.
While in mortality Christ was asked: "which is the great commandment in the law?" He answered it was love of God and others: "Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind. This is the first and great commandment. And the second is like unto it, Thou shalt love thy neighbour as thyself. On these two commandments hang all the law and the prophets." (Matt. 22: 36-40.) By pouring out his heart for others, Enos showed he had captured all the law and prophets in his heart.
At the point when Enos' heartfelt struggles are completed, and his compassion for his brethren is also "whole," his intercessory efforts were acknowledged by the Lord speaking to him.