This is just a common sense thing. Your body was meant to be used.
If you are a fat, out-of-shape, kid, you're likely going to have a life filled with various health issues.
If you are skinny, it's not quite as bad, but, you won't enjoy the benefits of resistance training.
If you've been to Wally World lately you understand that we have a health care PANDEMIC on the horizon.
Regular exercise (even if not resistance training), changes all sorts of hormones around that contribute to health, or the lack of it.
I'm 52 years old. Tonight, I held my heart rate at 145 for 5 minutes, and 165 for 20 minutes. (Max heart rate for me is 168 BPM, so I was training in "flat out" mode. My goal is HIIT at 190 BPM, like I used to be able to get, but..realistically, with my age, I'm probably not going to hit 190 any more.)
I have had LOW cholesterol all my life. I've had hypertension on and off over the years. Doctor says it's a genetic marker, but...the other day (side topic) ACA had an article about flaxseed. I got on it a while back. I'm sitting here right now with a BP of 110/72. Looks like something was missing from my diet. Doctor says I likely have a genetic marker.
Adrenaline, cortisol, and a long list of hormones change the way we age. Exercise does lots of good things.
Even after 38 years of lifting, and being very massive (5'5" and 200 to 230 at any given time) my heart is only 14mm in wall thickness (not bad for an athlete and very good for someone who packs as much muscle as me).
Here's some free advice: stay away from stuff like Red Bull, Red Line, and some of the over the counter go fast "supplements". They are terrible for you in that they will run your blood pressure sky high, and cause cardiac problems.