If you and I come to regard any aspect of this Christian life merely as a task and a duty, and if we have to goad ourselves and to set our teeth in order to get through with it, I say we are insulting God and we have forgotten the very essence of Christianity.
How have I got into this life…? Because the only begotten Son of God left heaven and came down to earth for our salvation, He divested Himself of all the insignia of His eternal glory and humbled Himself to be born as a babe and to be placed in a manger. He endured the life of this world for thirty-three years: He was spat upon and reviled. He had thorns thrust into His head and was nailed to a cross, to bear the punishment of my sin.
My friend, if you think of your Christian life in any shape or form with this sense of grudge, or as a wearisome task or duty, I tell you to go back to the beginning of your life, retrace your steps to the wicket gate through which you passed. Look at the world in its evil and sin, look at the hell to which it was leading you, and then look forward and realize that you are set in the midst of the most glorious campaign into which a man could enter, and that you are on the noblest road that the world has ever known.
~Martyn Lloyd-Jones, Spiritual Depression, p.200