This is a great question that can really determine whether your practice and lessons will be worthwhile. First, you should set a goal for the session, is your goal to improve your technique or a skillset, or both? If your goal is to work on swing technique, make sure to utilize the drills and/or training aids that help you accomplish the change. Put less emphasis on results and more focus on what you are physically trying to do. I’d recommend a lot of slow-speed swings when making a technical change, don’t be too proud to hit off a tee.
If your goal is skill improvement, give yourself a challenge and try to accomplish it. I have two examples… one is if you struggle with hitting fairways make a narrow fairway on the range between two targets and set a challenge point such as 7 out of 10 drives or more must be in the “fairway” in order to move to another club or go home for dinner. My other example is one of my long-time favorites… if you hit the ground before the ball too often, try making divots forward of the normal ball position. I use two tees as a gate/line (see photo) and make 3, 4, or 5 divots in front of the tees before introducing a ball to hit. You can put the ball in the same line and see if the “no-ball” swings translate when the ball is there.
Above all else when you are practicing, make sure to be alert. Be alert of your target, be alert of your lie, be alert of your rhythm and timing, and be alert of your contact and ultimately the feel of your swing.