The reality is most of the time, about 10 minutes in, the muscles are warming up, and you've got enough energy from it that you are willing to workout.
So when your self-talk starts telling you, "I am just too tired," or "I don't have time," remember... just do 10 minutes, and believe me, once you get started, you're going to notice you're able to do more, go farther, and finish the workout that you started!