If you want to get all kinds of dictionary, progress is defined as: forward or onward movement toward a destination. While health and wellness are not physical destinations per se, we can definitely see how measuring progress is important. Now there are a lot of ways to check in and scale physical progress. I am NOT a fan of scales at all, but they CAN serve a limited purpose. SOME of the measures that I use typically are: Improvement in energy, waist-line change, ability to move in new ways, improved cardiovascular limits, improved strength, improved agility, and improved attitude.
Now, some of those things are easy to measure, some not so much. But to ME, what progress really is, is the fact that you went out, and did SOME kind of movement and healthy eating with the purpose of improving yourself. If you can do that more days that not, you can easily and reasonably call that progress.
My functional definition for progress is: The intentional actions that you do to improve your overall health, in a positive direction. That is it folks because I do not want to get too technical. Start with that definition, and good things will happen.