“Put your heart aside. Duty comes first. But when fulfilling your duty, put your heart into it. It helps.” -Saint Josemaría Escrivá
“Never shirk the proper dispatch of your duty, no matter if you are freezing or hot, groggy or well-rested, vilified or praised, not even if dying or pressed by other demands. Even dying is one of the important assignments of life and, in this as in all else, make the most of your resources to do well the duty at hand.” -Marcus Aurelius, Meditations
“Good people will do what they find honorable to do, even if it requires hard work; they’ll do it even if it causes them injury; they’ll do it even if it will bring danger. Again, they won’t do what they find base, even if it brings wealth, pleasure, or power. Nothing will deter them from what is honorable, and nothing will lure them into what is base.” -Seneca, Moral Letters
“Character–the willingness to accept responsibility for one’s own life–is the source from which self-respect springs.” -Joan Didion
“On those mornings you struggle with getting up, keep this thought in mind—I am awakening to the work of a human being. Why then am I annoyed that I am going to do what I’m made for, the very things for which I was put into this world? Or was I made for this, to snuggle under the covers and keep warm? It’s so pleasurable. Were you then made for pleasure? In short, to be coddled or to exert yourself?” -Marcus Aurelius, Meditations
“Do your job.” -Bill Belichick
Very often the only reason to do something is because you said you would do it. It’s your job, your responsibility, your duty.
Let that be all the motivation you need.