We all multitask. Whether it’s checking email while talking on the phone or bouncing back and forth between two projects at once, it’s an everyday occurrence. We even pride ourselves on it. But the reality is, multitasking is killing our productivity and making us stupider.

Harold Pashler, a University of California scientist, recently conducted research on “dual-task interference.” His studies revealed that when people do two tasks at once, their intellectual capacity can drop from that of a Harvard MBA to an 8-year old.

Dr. Glen Wilson from the University of London also studied the impact of multitasking, with an emphasis on constant emailing and texting. According to Dr. Wilson, multitasking significantly reduces a person’s mental capacity. Women’s IQ scores dropped an average of 5 points. For men, multitasking was even more catastrophic; their IQ dropped 15 points. Fortunately, the effects aren’t permanent.

Still not convinced multitasking is bad for you? According to a study published by the American Psychological Association, it takes you 20 to 40 percent more time to get your work done when you’re multitasking. And if you’re trying to learn something new, it’s much closer to the upper level.

You can’t be at the top of your game when you’re multitasking. Your ability to be quick on the uptake and pivot on a dime is virtually non-existent. Yet if you’re trying to master a new skill or become proficient in a new area, being an agile learner is crucial to your success.

Here are four simple strategies you can use to stop multitasking—and get your time and brain back.

  1. Don’t check email first thing in the morning.

    If you typically start your day by thumbing through emails on your phone or checking your computer, you’re immediately setting yourself up for failure. Instead of helping you clear through your workload, going through your email in the morning can actually distract you from what’s important to get done.

    You’ll find yourself responding to minor requests, helping others get their “to-do’s” done while yours gather dust. Then, before you know it, you read an interesting news piece or blog post, which links to another article and down the rabbit hole you go. Meanwhile, your IQ is dropping, meaning that it’ll be just that much tougher to learn new things or make sound decisions.

    Instead, check your email on a schedule. Pick three to four times during the day when you allow yourself to review messages and respond to them. And give yourself only a finite time to do it. You’ll be amazed at how much you can get done.

  2. Organize your day in work blocks.

    This highly underutilized strategy really helps you get a whole lot more done and more efficiently as well. Before you start the day, look for activities on your to-do list that are similar. For example, you may need to make ten calls. If so, clump these calls together and do them one after another. You’ll get on a roll and get them done much faster.

    Perhaps you’re working on a several projects that require research. If so, allot yourself a segment of time to dig deep into that. Maybe you’ve got several different client follow-ups to do. If that’s the case, do them consecutively.

    A really good way to organize your day is in thirty-minute increments. Do it in the morning, when you’re fresh. Even better, do it the night before. That way when you get to your office, you’ll be all set to go.

    Personally, I use 30/30, a cell phone app to keep me on track. It’s a simple task timer/organizer that motivates me to get things done on a timely basis.

  3. Create a single-focus environment.

    Distractions are huge time and brain wasters. Because they literally invite multitasking, it’s critical to keep them away from you. Start by clearing everything else off your desk, only keeping out relevant folders. Everything else should be stored away.

    If you’re working on your computer, check out these resources that can help create a focused work environment:

  4. These tools can protect you from yourself, ensuring that a moment of weakness won’t turn into a lost hour—or, worse yet, an afternoon.

  5. Totally, utterly disconnect.

    This may be hard to do when you’re trying to expand your network, create new connections, and drive more business, but turning off your devices entirely is a powerful focusing strategy. There are times when you just need to think without any distractions from electronic devices.

    You’ll be amazed at how much you can get done in periods of uninterrupted time. You can immerse yourself in learning something new, get to the root of a knotty problem, or figure out a fresh strategy to achieve your goals.

    To really disconnect, physically move yourself to a space where you can’t be interrupted by phones or people. Isolate yourself by putting up a big “do not disturb” sign. Or, go to a coffee shop to get yourself away from any potential interruptions.

Jumping back and forth from one task to another is the worst thing we can do for our productivity. Everything takes longer, so we wind up working into the evenings, crazy-busy, overwhelmed, unable to stay on top of it all. We also learn slower, forget more, and make poorer decisions.

Multitasking is out. Today’s leaders need to start bragging about our ability to “monotask” as a badge of intelligence and competence.

JILL KONRATH is the author of Agile Selling: Get Up to Speed Quickly in Today’s Ever-Changing Sales World. She’s also written Selling to Big Companies and the #1 Amazon bestseller SNAP Selling.