I found this Martin Luther quote in Elizabeth Elliot's book, The shaping of a Christian family.
Our natural reason looks at marriage and it turns up its nose and says, "Alas, Must I rock the baby? Wash its nappies? Smell its stench? Stay at nights with it? Take care of it when it cries? Heal its rashes and sores? And on top of that care for my spouse, provide labour at my trade, take care of this and take care of that? Do this and do that? And endure this and endure that? Why should I make such a prisoner of myself?"
What then does Christian faith say to this? It opens its eyes, looks upon all those insignificant, distasteful and despised duties in the spirit, and is aware that they are all adorned with divine approval as with the costliest gold and jewels. It says, "O God, I confess that I am not worthy to rock that little babe, or wash its nappies, or to be entrusted with the care of a child and its mother. How is it that I without any merit have come to this distinction of being certain that I am serving Thy creature and Thy most precious will? Oh, how gladly I will do so. Though the duty should be even more insignificant and despised, neither frost nor heat, neither drudgery or labour will distress me for I am certain that it is thus pleasing in Thy sight.