There is a definite zone. If you've ever done anything that you truly enjoy and requires intense concentration then you've been there. Might be mountain biking when you are rushing down the single track just a little faster than you know you should and everything is blurred in your peripheral vision and it seems like you can anticipate every rut, obsticle and jump on the trail as if you had esp. You know the ride is going to be perfect and the adrenaline rush helps make you more invincible than you already know you are. But if you slip out of The Zone you're a smear on the trail. Just a taco'd wheel, bent fork, smashed helmet, and a bloodied road rash carrying your bike out of the woods.
Computer programming can be the same. If I can get into The Zone then I can pound out elegant computer code that reads like Pulitzer Prize winning poetry. Like anything else, finding the zone takes effort. Maintaining the zone takes concentration. I love being in The Zone. It's frustrating when I can't find it. Sometimes you can find it, but something pulls you out of it for just a moment, then it's lost.