I'm also pretty young and have time to run&lift 5-7 times a week, so maybe I'm biased.
As they say, "you can't exercise out a good diet". I've been counting macros (MyFitnessPal) over the last few months, as dull as it is, and I'm in the best shape I've been in, probably ever. I'm also nowhere near my goal, but the progression is encouraging.
Also wear a fitbit, it's nice to hit my 10k, but it's not something I go out of my way to achieve (other than, perhaps, walking up stairs rather than grabbing a lift or whatever). I do, however, pay close attention to my sleep (I'm noticeably worse at work with bad sleep) and my resting heart rate (spikes hard after drinking, affects sleep).
TL;DR: I wish I'd put more effort in (wrt exercise/health) as a younger guy and this would be much easier now. Plans/routines are super important. Sleep/alcohol/lack of exercise/shitty food affects me far more now than it ever did. Effort and tracking is dull, but the benefits are worth it.
40 is also when many people who've always had high metabolism suddenly change and begin to gain weight.
While the article sort of points at 20-somethings as the Fitbit worshippers, it's not for them. It's for older adults who let life get out of control and are looking for some way to get back in shape. That's what I see on the streets, at least.
On the other hand, my mother is a bit compulsive about her fitbit, though I see some real benefit. On days where she sees she's below her target, she opts to walk when she otherwise wouldn't or goes outside for a walk to make sure she meets the target. It's definitely causing her to be healthier than she otherwise would be.
Err, machines can do that for you.