I ran/obsessed thru HS and D1 NCAA, maxing at 85mpw in college. Strict on sleeping, eating, drinking, the whole regimented lifestyle. Was it worth it? Who can say for certain.
I ran one post-undergrad year seriously and was in PR shape that whole year.
I then decided to call it a 'career.'
The next dozen years of training were like a paper airplane flight--- slowly wafting downward in both volume and intensity:
First year of decay was running about 5 times a week, no structured workouts, run hard during the run when feeling good. Could still run a mid-15 5k.
The next year I ran 3x a week and lifted weights consistently for the first time ever--gained weight, shredded physique, looked the best in terms of mainstream attractiveness. Women were sexually attracted to me for seemingly the first time ever. Could still run a 16:30 5k. Looked amazing with my shirt off.
The next 10 years: entered grad school, got married, had kids, and hit a low point of running MAYBE once every 1-2 weeks for 30mins by the end. Got 'dad bod'--soft tummy, beginnings of man tits, legs lost their beauty.
Hit "rock bottom" a year ago: grumpy, low energy, barking at wife. Ugly look with shirt off. Decided to get back in shape. Ran 3x/ week for 30 mins and bodyweight exercises: pullups, dips. Then got into cycling with neighbor. Now ride 4x/week. No running. Looking, but more importantly FEELING so much better. Feeling way better at age 37 than age 30.
To you young men: I am more convinced than ever that it is vitally important to stay vital and physically vigorous for physical health, but equally for your mood and mental health. My physical decline was so slow and gentle that I did not notice the mental/energy/mood/focus issues, but the change is profound. My age peers who have let themselves go look horrible and feel horrible. Keep fit for yourself, and also for those around you. I'm pretty upset with myself for "sliding" for a decade, but grab the future with both hands.