A.B. Simpson emphasizes the importance of maintaining focus on God's purpose amidst distractions and irritations that can sidetrack us from our mission. He warns against becoming absorbed in petty grievances or the affairs of others, which can lead us away from our divine calling. Simpson encourages believers to let go of these distractions and to press forward with determination, declaring, 'This one thing I do!' as a commitment to pursue the goal set before us.

0ne of Satan's favorite employees is the switchman. He likes nothing better than to sidetrack one of God's express trains sent on some blessed mission and filled with the fire of a holy purpose. Something will come up in the pathway of the earnest man to attract his attention and occupy his strength and thought. Sometimes it is a little irritation or provocation. Sometimes it is some petty grievance he stops to pursue or adjust. Sometimes it is somebody else's business in which he becomes interested, and he feels bound to rectify. Before he knows it, he is absorbed in many distracting cares and interests that turn him aside from the great purpose of his life. Perhaps he does not do much harm, but he has missed his connection. He has left the main line. Let all these things alone. Let grievances come and go, but press forward steadily and irresistibly, crying as you speed toward the goal, This one thing I do!