care to share the secret?
As you asked.....I stopped HITT and body building type isolation training. I stopped playing football, Rugby was ended for me when I got caught at the bottom of a collapsed ruck and folded in half, both shoulders touched (I was a winger).
I still wanted to train and be active so read a lot on how old time strength guys trained 'full body' (they had it right), I came across Kettlebells (and haven't looked back).
More recently I've started to learn how sitting down all day at work its making us immobile, we should be able to move freely and with purpose until the day we are buried, so I've started incorporating rolling and crawling in to my daily practice (takes 10-15 minutes every morning) and walking more.
Everyone can benefit from moving better (reflexive strength) check out
https://originalstrength.net/ its so easy to do...start here!!!
If you are interested in other training (Kettlebells, Barbells, bodyweight) check out
http://www.strongfirst.com/I'm not saying HITT is the devil, but it has to be used in the right way, as the name states its intensive and should be done for short periods e.g. weeks not months or years and only when you have a good strength base and no injury issues, also HITT gets bounded around when a lot of programmes aren't HITT.
There is saying in the S&C coaching circles that its easier to tire someone out than make them stronger (look at any boot camp), this is very true.