If you're a fan of Getting Things Done, you're familiar with the Four Criteria Model for choosing tasks. It's where the rubber meets the road in GTD, because it's the way you decide, in the moment, how any one of those wonderful tasks you've been tracking in your big system actually gets done.

As common sense as it seems to GTD'ers, this model is one of the more controversial aspects of Getting Things Done for a simple reason: it posits that priority is not the only factor in deciding what to do at a given time. It's just one of four factors, which include, all told:

1. Context - Where are you? What tools are available? What are the limits and possibilities unique to this moment?
2. Time available - Do you have, for example, 30 seconds, 30 minutes, or 30 hours available to you right now? What tasks could you accomplish given the time you have?
3. Energy available - Are you full of energy, is your ass dragging, or are you somewhere in between? Which of the tasks on your list could you finish, given that energy level?
4. Priority - If you had access to all the tools, opportunities, time, and energy you needed, what's the most important or time-sensitive thing you could do right now?

When I'm helping coach people on getting it together, they're often puzzled by this seeming bit of new-agery -- partly, I suspect, because most of us have been conditioned all our lives to think that pre-ordained Priority stamps always trump everything, all the time, always, forever, in all cases, end of story. But is it true, reasonable, or even physically possible to always work this way? Can you will yourself into doing only your identified high-priority items anytime, all the time?

Nope, and I'll show you one reason why.

Stressful times for Worker Bee

Let's look at a few challenges that, over the past six months, have faced a notional Worker Bee, leading him to generate high-priority tasks.

1. You learn you got a citation from those choads in the Homeowner's Association, and they declare that if you don't remove that El Camino from your front yard today, they'll start fining you $200 a day.
2. Your favorite client emailed you a freakin' week ago, and you still haven't responded. You fear that your relationship will be permanently damaged if you don't respond this morning.
3. Your bank account is overdrawn and you have to make a deposit or else the late fees and penalties will go up and up and up.
4. Your sister leaves a voicemail saying that if you don't pick up the crap you left in her garage, she's throwing it out tomorrow. Your Boba Fett action figure and Dungeon Master's Guide are in that garage, and you can't bear the thought of losing them.

All extremely high priorities to this person, and for good reasons, each. So he has to do them all the second they come up, right? Well, maybe.

Worker Bee buzzes into high-priority action!

But let's look at some additional factors in the worker bee's life that affect the immediate do-ability of each of these high-priority tasks -- things for which raw priority may not account.

• #1 The errant El Camino citation comes up while you're in Kazakhstan, and the only keys to the car are currently in your right hip pocket -- which is also currently in Kazakhstan. How will you move the car right now? You can't. The context is wrong and, by extension, you don't have the time (to fly overseas) to take care of it by sundown today. **BZZZZZT!**
• #2 The late email you wanted to send is briefly on your mind as you sit in the Emergency Room holding your sick kid. Well, for one, your priority just got changed for you. And for another, you don't have a computer or smart phone with you anyhow. No dice, Superdad. **BZZZZZT!**
• #3 That stupid overdraft shows up via BlackBerry while you're on a quick break from a marathon meeting with your bosses. But you don't have either your checking account number or your bank card with you, plus you're due back in that career-defining meeting in 20 seconds. **BZZZZZT!**
• #4 Your beloved geek toys' endangered status update arrives at the very moment you're vomiting yellow, half-shrimp-filled goo thanks to the food poisoning you just picked up from that leftover quart of paella. If you weren't blowing golden chunks, you might be able to make the trip to her house in time, but for now, it's probably a non-starter. **BZZZZZT!**

So, did I cheat to start with just priority and only later give you the contextual details? No, not really. That's actually the point.

Priority mania considered harmful

On some level, this happens to you every day, but even the hugest priority can only be seen clearly in terms of the big picture. Priorities don't care who they compete with, and, from one vantage point, that's kinda what makes them priorities.

Hell, Priority Task Number One (flagged “HIGH PRIORITY!!!”) could give a fig whether “HIGH PRIORITY!!!” items 2 through n ever get a single gulp of oxygen. Priorities, left to their own devices, are selfish bastards. That's their job.

But, remember: priorities represent a snapshot in time and space -- they may escalate, de-escalate, disappear, or, more often than not, they'll be subject to getting bumped by both bigger priorities and by the immutable limitations of time, space, and being a corporeal (sometimes vomiting) human being. Sucks, but it's life, right?

Negotiation skills

The first thing to know is that in GTD, there are three ways of resolving a problematic commitment -- you can either:

• complete it (jump on a plane; borrow a computer; cancel the boss meeting to fetch your bank card; drive while barfing copiously all over yourself)
• renegotiate the commitment (sweet-talk the ultimatum givers; plan to apologize later to the client; reschedule the meeting)
• break it (suck up the fact you're getting fined, losing a client, or never seeing your Dungeon Dice again, then just pick up the pieces later on)

You can choose how you deal with high-priority items that can't be done when and how you'd like, but you'll never bend the space-time continuum. Plus, you'll probably strain your lower back trying.

Who's flagging who?

This is not by any means to say that priorities aren't important. I mean, that's why they're called priorities. But you have to take care to understand the larger picture at all times, and to not become so obsessed about priority-centric planning that you create impossible situations and unreasonable expectations for yourself. It's a sure path to serial procrastination for one thing.

When you're self-aware and honest enough tomorrow morning to say "Screw it, I'm going to sharpen pencils for 10 minutes" or "You know, this deadline is impossible without flipping my life upside down" you're turning a corner. You've begun to permit yourself a broader understanding of the real world, in which, as the sole traffic cop for your life, you are in the unique position to decide what's do-able at any given moment.

“But...I'm, like, important”

I imagine I'll hear from people in comments who have the kind of incredibly important job where Horrible Things happen if they don't prioritize the shit out of everything and do it all flawlessly each day. Or maybe they work in Candy Land, where lollipops grow on trees and any perceived priority can be made to trump reality as easily as delicious nectar can be sipped from a flower. But, for the rest of us, I stand by the point: obsess single-mindedly over priority at your peril.

Unless you can always satisfy the big red letter commitments you've created for yourself -- as well as the ones that are constantly being generated for you by others -- an obsession with priority alone is pointlessly stress-inducing, unhealthy, and unrealistic. The truth is that sometimes you have crap days, pencils need to be sharpened, or maybe you just don't have the tools or energy to do what you want the second you want. That's life, pal. Deal.

So, instead of having an aneurysm about it, just rally, and do what you can with what you've got. That's all any of us can really do, and faking it in order to feel more productive (or more important) gets you no place fast.