I always considered that work is not life(with a few exceptions that are really passionate about their work) and life usually begins after 5PM.
Most of us choose a workplace just to make an income and when you only work for money these endorphins that you mentioned in the post are floating away from your brain waiting for that deep breath of fresh and a walk that relaxes you.
My endorphins usually come from walking and biking as I do that often after stressful times and sometimes driving also.
I find it very important to have such activities that involve more the soul than the mind where you can feel nature's connection.