In my teens and twenties, I competed in several triathlons before doing four marathons and an ultra (the Doc Holiday 35-miler), and through those amazing experiences thoroughly got long-distance and competitive running into ... and then out of my system.
I loved it and I have no urge to return to it. As I mentioned in an earlier post, a few years ago I walked away from running and jogging, and I haven't looked back since. That's both because I love walking so much and because I've pretty consistently been pursuing a body weight workout routine.
I try to change up the workouts every few months, just to keep things from getting stale. I'm currently on a day-on, day-off routine with three main days in rotation: 1) a focused pulling day (various pull-ups and rows), mixing in leg work; 2) a focused pushing day (various dips and push-ups), mixing in leg work; and then 3) an improvisational movement day, working my whole body as I feel inspired to do so (typically circuit based). This iteration of the routine is feeling pretty good, and I likely won't change it for a spell.
And then I walk every day.
So what about the blood-brain barrier? Well, I tend to think that regular movement and strength-based exercise is working for me. At least for now.