I, for one, can do heavy bodily harm to myself if I attempt to live in this state for long periods. It turns out my mind is much stronger than my body. Perhaps the flow state removes the regular messages the body sends when it's had enough.
Either way, life without play is dangerous for me.
One of my tricks is keeping a glass of water at my desk. Filling the glass is a break. So is emptying my bladder. The break lets you reflect, and decide if you’re chasing your tail or doing something questionable.
Drinking is also a work appropriate fidget. Sip of water instead of tapping a pen or bouncing your leg. And easier on your kidneys than overdosing on caffeine all day.
Either way, life without play is dangerous for me.