People will get into the habit of doing the same thing over and over again, and you'll stop seeing changes in your body. If you add variety and spice things up, I think it'll help you to stay motivated.
There are days when I don't feel motivated and I don't want to get up to go to practice. I'm a very goal-oriented person, so I set short-term goals and try to reach those goals. And when I have those days, I think about those goals, and it gets me motivated.