The other day I was in the gym and I saw something that inspired me to write this blog post: a man who was reading the newspaper between sets. Actually, he wasn’t just sitting and reading the paper. No, he was pacing back and forth, all while leaving a towel on whatever machine he was using.

If this guy had just been reading the paper in a corner, it would have been weird. But taking up space by pacing around, taking forever between sets to read the paper and hogging the equipment made it downright rude. Did I mention that he was also wearing headphones? Or that he periodically switched from his newspaper to his phone?

This person was attempting to do all of these things simultaneously:

  1. Work out
  2. Read the paper
  3. Listen to music (or at least some kind of audio)
  4. Check stuff out on his phone

All philosophical rage aside, this is, from a cognitive perspective, a terrible routine. Let’s explore why.

Brain Fuel

As I’ve discussed in previous posts, the brain requires a supply of glucose to run. Each time you do anything that requires cognitive input, that supply goes down. Tasks that require intense focus (which usually means engaging the power-hungry working memory system) will plow through fuel like crazy, while more automatic tasks (like walking down a familiar street), will only go through a minimal amount.

There is, however, a slight nuance that hasn’t been covered here before. Even though you can predict that certain tasks - such as playing a game of chess or writing code in an unfamiliar programming language - will burn through lots of fuel, many people discount what happens when you switch regularly between tasks. Stopping what you are doing and then diving into something else goes through fuel. Even if the task is not particularly demanding, the constant switching can rapidly deplete your brain’s energy supply.

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This is because each switch triggers large changes in the blood oxygen level-dependent (BOLD) signal in the prefrontal cortex and several other brain areas, and these changes in oxygenation level almost always mean glucose will be metabolized.

In plain English, enough small tasks will burn through the same (or more) energy as a small number of big tasks.

What’s worse, you’re plowing through that energy without getting much back. Consider the difference between focusing on a project you really care about (writing a book, painting a portrait, etc.) and spending your time browsing your various social networking apps. Both choices will deplete your fuel supply with enough time, but only one will provide you with real results. Even though switching around between your email, Facebook page and Instagram account will make you feel tired, you will have accomplished very little.


In 2009, a group of psychologists at Stanford decided to study whether chronic multitaskers were good at juggling so many things at once. Here’s what Clifford Nass, one of the researchers, had to say (as quoted in The Organized Mind by Daniel Levitin) about what they found:

We all bet high multitaskers were going to be stars at something. We were absolutely shocked. We lost all our bets. It turns out multitaskers are terrible at every aspect of multitasking. They’re terrible at ignoring irrelevant information; they’re terrible at keeping information in their head nicely and neatly organized; and they’re terrible at switching from one task to another.

You can read the study they conducted here.

These findings are in line with a variety of phenomena that we modern humans come across on a regular basis. For example, if you’re driving down the street and find yourself behind someone who’s driving ridiculously slow and swerving. You pull up next to them to see if they’re chugging a bottle of Vodka, only to find that they’re texting away behind the wheel. In fact, this is actually more dangerous than if they were going bottoms up with a bottle of booze!

The reason you can’t multitask is pretty simple: multitasking is mostly a cognitive illusion. Your brain doesn’t actually handle lots of different tasks at the same time, it operates in a very binary, on/off sort of way. You’re confined to putting most of your attentional resources to work one task at a time, and what is viewed as “multitasking” is really just rapidly switching between those tasks.

The end result is that you don’t do anything well. Whatever it is that you’re trying to juggle simultaneously, you will suck at it. Period.


Multitasking is a bad idea for a variety of reasons. For one, you burn through your brain’s fuel like crazy and make yourself feel exhausted - even if you didn’t actually accomplish anything in the process. Secondly, whatever gets put into your multitask queue will suffer. You may accomplish a goal, but you’ll almost certainly do it in more time and have a far less desirable end-product.

We live in a world that is often described as fast-paced, and many employers believe that their workers should be excellent multitaskers. The problem is that nobody is an excellent multitasker. Even worse, nobody’s a multitasker at all - good or bad! We’re all just switching very quickly between things, depriving ourselves of precious brain fuel and annihilating the quality of whatever it is we’re working on.

Let’s revisit the person I came across at the gym. While this guy probably thought he was being a resourceful, productive person, in reality he was only putting himself behind. He was compromising his results in the gym by taking huge breaks between sets, being extremely rude to those around him by taking up large amounts of space and occupying equipment and, in all likelihood, not taking in most of what he was reading (especially since he was wearing headphones). His constant task switching made him worse at everything he was doing, with zero benefit. It’s actually worse: he received negative benefit. He would have been much better off doing each of these things separately, preferably from the comfort of his own home.

If you want to truly do outstanding work and be prodigiously productive, you must make a commitment to focus. It’s a rare person who can tune out email, social networking, phone calls and other energy-sapping distractions whenever they need to get something done. By dedicating the limited energy you have at your disposal to tasks that you care about, you can transform the quality of both your work and life. At the end of each day, you can reflect on what you’ve done and know that you not only accomplished something, but didn’t exhaust yourself needlessly with inconsequential tasks.