So for aerobic exercises, you could track the amount of time you can spend on a given exercise. So if you're doing something like wall sits and you can spend 45 seconds in the position on one day, then 50 seconds the next, that's an effective way of tracking your progress. It's the same thing with intensity: how long can you perform the action. Another way of gauging it is distance in a given time. If you run 5 miles in 30 minutes one day and 5 miles in 26 minutes the next, that 26-minute run was more intense than the longer run. When it comes to weight training, you typically look at the amount of weight and the number of reps.