Yea, and when you do not cry unto the Lord, let your hearts be full, drawn out in prayer unto him continually for your welfare, and also for the welfare of those who are around you.
--Alma 34:27
Amulek makes a distinction between crying to the Lord and offering constant, silent prayer. To cry is to beg and beseech with strong emotion. I face times when I must be fully engaged in prayer, when a sedate and pleasant prayer will not do. When my heart is broken and my limits are stretched and the depth of my soul heaves very close to the surface, a cry to God is the most direct route to aid and comfort in desperate moments.
I cannot constantly be wrought up, however. When the crisis has passed and peace has come, I still have to function in the world. In the routine of daily life, quiet, calm prayers of gratitude are also acceptable to the Lord. Like Teviah in Fiddler on the Roof, I find myself speaking to God throughout the day. A "thank you" here and a "please help" there keep the lines of communication open between me and my Heavenly Father, with Jesus and the Holy Ghost always listening in on the party line.
