In my opinion, the most important thing that one should learn during the course of a Ph.D. and postdoc is how to be an independent researcher, directing one's own line of research. Part of that is learning how to acquire your own motivators. If you need external motivators, the academic world is full of deadlines that you can apply to yourself: conference deadlines, journal revision deadlines, project review deadlines, grant application deadlines, collaborators who need you to hold up your end of a bargain.
If you find a framework of deadlines is important for you, you should be able to arrange for weekly meetings with your advisor, which can provide a running set of deadlines for you to target. Early on in your program, much of the goal-setting is likely to come from your advisor. Later, as you mature as a researcher, hopefully it will shift to be more coming from you. Depending on your field, your advisor, and your personality, that may come sooner or it may come later (which is why I included postdoc above).
At the same time, I will warn you that deadlines and short-term goals are a good way to avoid one of the hardest things about research: finding the perspective to step back, take a look at the bigger picture, and figure out what is actually important to do. At one point in my Ph.D., my advisor told me that now was the time that I needed to just go sit under a tree and think for a while. He was right, and I didn't like what I found when I stopped doing and thought seriously about how those things related to my actual dissertation goals.
It's entirely possible to do a Ph.D. and postdoc in an entirely project-focused and deadline-driven way, while never developing as an independent researcher, but instead becoming sort of a "super technician." In fact, pressure from grants provides incentives for professors to push their students to do so, creating deliverables rather than learning to self-direct. You can have an excellent career in industry or a non-PI position in academia on the basis of such work, and that's fine. If you want to be an independent investigator leading your own line of research, however, then at some point across Ph.D. and postdoc, you will need to learn how to handle the dreadful freedom of managing your own time and expectations.