'Ah,' we say, 'the same old thing week after week.' That is our attitude towards our life, and ... we become weary ... If you regard the Christian life as a dreary task you are insulting God ... 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. The Christian life is not a task. The Christian life alone is worthy of the name life. This alone is righteous and holy and pure and good. It is the kind of life the Son of God Himself lived. It is to be like God Himself in His own holiness. That is why I should live it. I do not just decide to make a great effort to carry on somehow ... How have I got into this life — this life that I am grumbling and complaining about, and finding it hard and difficult? ... there is only one answer ... 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. That is how I have come to ... this.
... 'Be not weary in well-doing.' My friend, if you think of your Christian life ... 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 ever enter, and that you are on the noblest road that the world has ever known.
Martyn Lloyd-Jones - Spiritual Depression, pp. 199-200