I'm jealous of Powerlifters, marathon runners, and Crossfitters. There. I said it.
If you don't know anything about these sports, let me fill you in. Powerlifting is a sport where you try to accumulate the highest total number on three lifts - bench, squat, and deadlift - in a single day (a meet). Some associations allow special clothing to be worn, some don't, some drug test, etc., but the basics are there. A higher number is better.
Marathon runners try to run their marathon as quickly as possible. The lower the time, the better.
Crossfit is a bit more complex. It's a training system with really varied training (mixed modality, where you train for many different components of athletic performance to try to be as well rounded as possible), but one of the sport's hallmarks is a series of named workouts (all with girls names, like Fran) that are hit every so often. Crossfitters can always compare their performance with a sentence like, "Hey, I just did a four minute Fran. How's yours?" (By the way, I have no idea if a four minute Fran is good or bad, it's just an example).
Why am I jealous? Because in all these athletic pursuits, and in many others, the athletes have very clear ways to measure performance. You're a powerlifter with a new diet plan and your total dropped by 50 lbs.? Maybe you need a new plan. You're a marathon runner who gained some weight and your times improved by 8 seconds? Maybe the weight was needed. Hopefully you see my point.
As a martial artist I don't have any numbers to work with to assess my performance. I can tell when I've improved - when my kata are cleaner and crisper, when my sparring is more on point - but I have no real way to measure progress. I can't say, "my kata were improving at X rate, but when I dropped grains from my diet they improved at Y rate instead."
I'd love to have a very accurate grading system for movement quality. You send in a video of your Taikyoku I or something and get back a three digit score on how well you're moving. Whoever/ however this was done it would have to be repeatable - that is, if you sent in the same video again, it would have to return the same score. It's not really feasible. Any person who would be capable of that kind of feedback would probably have better things to do than spend all day looking at videos of idiots like me looking to measure their progress.
The best we can do is some sort of self-scoring system. We can give ourselves a score, say out of 20 poitns, for our technical proficiency, then out of 20 for our energy level, etc. I suspect it would be worthwhile to keep a training log that recorded those scores, but they're too arbitrary to be as useful as, say, a powerlifting total. Does anyone think that a score from your first year of training would correlate meaningfully with your score after 20 years?
One last point: don't make the mistake of thinking that progress in ancillary exercises is the same as progress in your art. Being able to do more pushups might be a good thing, but it doesn't necessarily mean you've become a better karateka. It just means your strengh or strengh/endurance has improved, which might mean you've gotten better, but it might have come along with a decrease in actual power output, which would be bad. Don't get bogged down in trying to hit 100 pushups at the expense of your art.