I used to race endurance sport. I pretty much stopped doing that mid-2018. It takes ALL of your effort, focus, money, and time to race at an elite level. The cost is everything, your whole life. The benefit was significant personally, but eventually the training and racing becomes more of the same - been there, done that. The cost remains the same - everything. So, after 4 or 5 years of racing, I decided it was enough - the cost-benefit was no longer attractive.
There are other things to do. I still run across the grass and around the neighborhoods on occasion, ride bikes casually, and can swim across the lake on a whim. Weights and other exercise is taken daily. I'll never be as fast as I was during the elite triathlon adventure. When you're done, you're done. Physical fitness was at an almost unimaginable level during that period. Current fitness now includes other things, like being good at being a friend, reading financial statements, picking stocks, carrying heavy backpacks, shooting arrows, backcountry meat processing, gardening and being nice to people.