If it works for high school athletes, it works for people who are ten years older, too.
Personally, I look at results. If you can be motivated by Richard Simmons, go for it - the guy is 15 years older than my dad and is still in damn good shape. If you can be motivated by Crossfit, go for it, as long as you aren't getting scoliosis for time. If you can be motivated by the standard bro-split, that's great. Everyone is different.
All I can say is that when I show up to the gym, I'm lifting heavy, and I'm lifting to get freaking tired. It's worked for me. If flouncing on the elliptical for half an hour and doing 3 reps of 10 to success isn't doing anything, you might want to consider changing it up.