I lived a fairly athletic life growing up. I swam competitively from the age of four and didn't stop competing until graduating High School. Aside from developing a freakishly strong cardio endurance and some very sore shoulders, swimming didn't prepare me very well for being a gym bro with plates and bars.
When I started hitting the gym I'd always go too hard too soon. By this I mean I'd go every day for a couple hours and get so obsessed with pushing heavier weights that I'd routinely compromise my form and not give myself adequate rest. After months and even years of plateauing, overtraining, and overtraining related injuries, I've finally started to break through into new territory by simply doing less.
My overtraining injuries were usually in the vein of tennis elbow, hyper extension, and the occasional sprain during fairly boring movements. The tennis elbow was due to not enough exercise diversity and having poor form. The hyper extensions would occur due to swinging through the motion rather than remaining slow and controlled. And the occasional sprains were a result of not providing the body enough rest between workouts. It was also extremely inconvenient to hit my calorie targets, which was around 3000 calories a day (220 pounds, 6'2", ~12% bf). When I was hitting my calorie targets it was a full time job and I looked and felt like an ox. I always felt stuffed and had to eat even when I had absolutely no desire, it was gross.
At a certain point I decided I'd get down under 200 pounds and maintain a leaner build, since it'd be easier on my joints and stomach.
Nowadays I perform a medium to heavy full body workout three times a week, and my aesthetics are the best they've ever been. I experiment with a simple calisthenics routine that has an adequate warm up, and I perform a simple yoga routine every morning to stay limber. I'll have to link the yoga video once I find it again, I memorized it long ago when I had an extremely tight and painful lower back (now I'm pain free). In my workouts I opt for lighter weights and slower, more deliberate motions. And as many body builders tell us to do, I give myself 48 hours to recover before working out again, thus the M-W-F cadence.
My workouts are always balanced between chest, back, abs, and legs. While resting one muscle group I'll be warming up another, and as I finish sets for one exercise I'll already be on the second set of the fresh muscles. I stick to four to eight sets of four to eight reps, graduating myself to a harder progression once I'm hitting multiple sets of eight reps without much trouble.
Diet is obviously essential to a good physique, and after experimenting for a few years I've found that cyclical keto works the best for me. Rather than couting carbs and assuring I'm in dietary ketosis, I'll simply eat meat and veggies for all of my meals except for those immediately before or after a workout. For those meals surrounding a workout I'll add a small helping of rice and raisins or other fruit to have adequate glycogen replenishment. The keto snobs will likely say my diet is closer to low carb than cyclical keto, but imo that's splitting hairs. I've developed a good gauge for when I should have some carbs and the craving is always satisfied with an extremely small amount, like a cup of rice or less. In a given week I may consume three cups of rice total. I also don't consume any oils, I cook everything in boiling water with very light seasoning.
I'm hovering around 195 pounds and can probably drop more, but feel quite healthy at my current weight. I've recently become curious about fasting, as the couple times in my life I've tried it I felt very light on my feet and clearheaded.
As always, the key has been to remain consistent and patient with myself. The takeaways here are that it's easy to do too much. For exercise, your muscles make their gains during rest. If that rest isn't facilitated constantly, you're setting yourself up for injury since you'll be causing a net positive number of micro-fractures and micro-tears, aka overtraining. It's worth it to even have a week break every three months or so, just to make sure you're completely healed and not overtraining.
For diet, it's easy to consume way more carbs than your body needs. Carbs are extremely cheap to cook up and they provide a bloated feeling, so every restaurant is happy to shove them in your face. If you stick to meat and veggies, you'll be surprised at how much food you can put away; this is mostly because you're not spiking your insulin nearly as much as you would with carbs. Once you've weened off carbs you'll realize how few of them you actually need.
So for both exercise and diet, less has been more. Hopefully these nuggets give you some inspiration to experiment and find your sweet spot as well.