To find out how to get it back, you first must discover how it was lost. Either you found yourself in a new, un-easy situation, or your old, easy situation got dull. Without knowing which, it seems to me that either way the answer is to do something new and put yourself in the most relaxing circumstances possible. Being alone in nature for several hours usually works, almost forces the brain to ease up, but your results may vary.

I'm assuming it has to do with your amygdala having the fight-or-flight response triggered in you, leading either to constant active unease or passive burnout. A body in anxiety sees relaxation as alertness-compromising safety risk.
You have to impose a feeling like you're diving, and relax so much that you would almost collapse down onto the floor, but you're to hold yourself on your feet even if you drop your stance. You may have your first time while you sit. Your task is to imprint, memorize, recall this flow of life feeling of getting as close as possible to the very fall/stand boundary.
At least that's what had helped me.

>>156195
This sensation was maddening. I had this constantly in the latter half of college. All these things I could to do relax and take it easy, but the constant nagging in my body that I'm wasting my time and have to be doing something or other sucked all the life out of enjoying things.