Imagine not being able to sit down.

We probably all know someone confined to a wheelchair, unable to stand up. But imagine that you couldn't sit down. I know it sounds far-fetched, but it's actually happened to me, more than once.

I have a recurring back pain that is so intense that it's landed me in the emergency room in the hospital more than once. It's shocking and debilitating: I actually had to crawl to the car once to have someone take me to the hospital.

There's apparently nothing that can be detected: I've had an MRI that found no deteriorating disk or cancer or whatever, just this lightning strike in my back that makes all movement, up or down, impossible. All I know is that, once in a while, something in my back "goes out" and I'm left in severe pain and unable to move about the way I'm used to doing.

(Those of us who have suffered these episodes know what I'm talking about; the rest of you just have to take our word for it. It hurts a lot, on a level that Doan's pills don't alleviate. It's way down, bone-deep, nerve-deep, and you've never felt pain like this before.)

Anyway, when I've had these "lightning strikes" in the past, I've noticed that I'm only relieved of the pain when I'm lying down or, when I force myself to stand, on my feet. When I'm standing, I do have to hold to anything nearby, whether a railing or a friend or a countertop: anything to keep me upright and, hopefully, not about to experience a "knife in my back" that will drop me to my knees. Where this came from I don't know. I think it may stem from a weight-lifting accident early in my adult life, but I can't be sure.

But my point is that, when this is going on -- and it does come and go, sometimes lasting a few days, sometimes months -- I can't sit down. I can lie down (maybe with a heat pad or ice: I'm never sure which one, if either, does any good) or I can stand, with support, and even try to walk around (very carefully, very slowly). But I can't sit down. It's just too painful to stand back up.

Think of the times every day when you sit down. For breakfast? What if you had to eat it, in your own home, standing up? You get into your car to go to work -- but, uh oh, you can't do that because you'll never be able to stand up once you get out of the car. You'll be bent over and in pain. (Your body bends itself to compensate for the pain, trying to get away from it, and it's not something you can control: you really are bent over, and still hurting. And people look at you.)
You can't drive -- the worst -- and you can't sit once you get to work.

So maybe you call in sick: "I've got this back problem. I think I'll be okay tomorrow." But you're not going to be okay tomorrow, and you have to call in sick again. People at work are probably starting to wonder if you're pulling some kind of scam.

In the meantime, you can't sit down. You can take to your bed, which you don't want to do, or you can stay on your feet all day, which gets kind of wearing on your feet and legs. Suppertime comes and goes at home: you can't join the family at the table. You stand at the kitchen counter, leaning against it, in pain, and try to smile.

You think again about all those times you sit down during the day: in the car, at the office, over coffee, at dinner, etc. You can't do any of them because not only is the sitting painful but the getting up is likely to send you to your knees. (And you're already crawling to the bathroom at night when you have to go and then lifting yourself onto the toilet, where the pain is unavoidable but no less present.) You think of yourself as some kind of mutant who can stand and lie down but not sit. And you're wincing all the time from a pain no one else can see.

And that's part of the problem. A back ailment can't be seen. A person in a wheelchair has a visible disability. So does a cancer patient with an obvious wig. As does an obvously overweight person. But a back problem -- like depression or schizophrenia -- is invisible. Your family and friends and colleagues just have to take your word for it.

It hurts, you say. Real bad!

We all take for granted so much of our human existence. It's only when something goes wrong, when we're deprived of a sense (sight, hearing, etc.) or an ability (movement) that we realize how tenuous is our hold on what we call being human. Being deprived of the right to sit is, admittedly, minor compared to those folks in wheelchairs -- especially since, in my case, it's temporary (I do get okay finally) -- but it's a reminder that we shouldn't assume an inalienable right to anything. It can all be taken away in a flash. A car accident, an illness, a bad decision, even a bad gene.

I'm sitting down right now as I type this, but there was a time, only a year or so ago, when I couldn't have done it. In fact, there was a time I was lying on my back on the floor of my office, my laptop computer on my lap, a heating pad on my lower back, thinking: Shit, I'm going to have to crawl to the bathroom again. I hope no one is watching.

Suppose you could only lie down or stand up but not sit. Think about it.

Value what you have and take nothing -- repeat, nothing -- for granted.