I don't think the Saints really knew if they were completely fulfilling the will of God. If they are any type of human who loves the Lord, most of the time they were probably chastising themselves for raising their voice in a poor tone and worried about the mandate for loving thy neighbor in all ways.
God teaches us vain and selfish creatures to mainly love Him and love our neighbors. There are detailed aspects to this in the scripture but the overriding theme of life seems to be, "What am I supposed to be doing for our Lord?" This is the question that is just a daily question.
For myself, it is a frustrating question. All of the little things matter and they matter to God. It is His will to be concerned with the details and love, love, love. The frustrating part comes in for all the things that we have no control over. The world in my view today, is disgusting. I am 33 and even though I know many disgusting things have gone on for centuries, it has disgusted me as a history teacher and it disgusts me as a participant in this present time.
I thought for a minute today that, 'Wouldn't it be nice to have lived in the 1950s?' Not that the things happening now would be any different but just in secret. So I am charged with living in this time period and I am called by the will of God to live with joy and a shining Light of Christ for all to see. Seems pretty darn impossible and I have very little knowledge as how to move past the enumerable barriers that want to break the spirit. (I admit I have been discouraged by persecutors)
This is where one of the most important phrases that Christians can know comes into play for me. "Look at the birds of the air: they neither sow nor reap nor gather into barns, and yet your heavenly Father feeds them. Are you not of more value than they?" Matt 6:26 Last week's Sunday reading is a reminder and a connection to the life that God the Father calls us to live no matter the conditions. It's not the value that God puts on our beings so much as the distance He will go to provide for our every spiritual and physical need. Therefore, I can only assume that the small duties that Christ calls me to do, to know the Father are those that are God's will. As for the limitations of my sin and the call to sainthood, I try to remember that God the Creator will try infinite ways to help me make right decisions and by the Holy Spirit, do His will. The world of deceit will always crumble before the righteousness of truth that is Jesus Christ the Savior.
