What I do - My daily exercise routine is - 2 hour cardio (hike, cycle, swim if summer) and every other day 4 sets of 20 chin ups or 4 sets of 20 triceps dips for strength. Cardio takes time, strength does not as I have bars right close to my computer in my office.
Sure, one day it will all go downhill and I'll croak but for now I enjoy the life just as well as when I was 20.
Do you have a full-time job? That would take most of my evenings if I decided to do it.
It's been clinically proven to help with vascular health (HDL cholesterol level goes up) and increase insulin receptiveness.
As for job - I am on my own and develop products for clients and for my own company.
I feel that from the biological point of view, the brain evolved to serve the body (mostly for locomotion) and it's level of function is tightly related to fitness in general