This may seem obvious as a workout tip, but plan your workouts before starting. Figure out what your goals are for the months ahead, so that you can figure out the general types of shorter term goals to set. That way you can set specific goals a week or two ahead of time, and have a workout planned out before starting it. Sometimes you won’t be able to follow that workout, but most times you will, and the times that you plan a workout and then can’t follow through will be far fewer than the times you don’t plan a workout and then half-ass it.
For my weight lifting, I like to plan where I will be a month or two ahead of time, so that I can set up 2 to 4 week routines. Going into a week, I like to know which days I am going to workout, and which muscles I am going to work on those days. I do not always have the exact workout planned out for the entire week, but I will always have at least the next workout down on paper a day or more ahead of time.
There is much less thinking involved and fewer chances to be lazy when you can just look at your piece of paper to see what to do next, especially when you are circuit training. If you track how much you lift and how many reps you do, then it is easy to see how many sets you actually have done instead of trying to misrecall. If you use a small notebook (as I do) then it is easy to look back at prior workouts to gauge about how much you should be lifting that day.
Give it a try. See if your workouts improve.