Our workdays often are governed not by priorities or desires but by what’s screaming loudest and closest in our faces. Well-intentioned as you might be about having a productive day, it’s easy for the hours to pass in a flurry of emails, meetings, and demands that eat away at your time like a tapeworm — stealthy, but destructive.

Sure, there are tons of productivity hacks out there — from to-do lists to time-management apps to mindfulness exercises. Everything seems to work for at least a short while, until the suck of everyday demands takes over.

Here’s an alternative: instead of thinking about your day as one long to-do list or trying on different time-management exercises for size, take a closer look at the science of how your brain functions throughout the day and try to match the right tasks to the right mindset to help maximize productivity.

To start, let’s think about some crucial turning points in the day.

Cherish your first three hours

The first three hours of your workday are your most precious and productive, according to psychologist Ron Friedman.

Rather than leaping into your email inbox, checking your voicemail, or responding to other people’s requests, focus those first hours on the work that’s most important to you and your job.

“Typically, we have a window of about three hours where we’re really, really focused. We’re able to have some strong contributions in terms of planning, in terms of thinking, in terms of speaking well,” Friedman told Harvard Business Review. “If we end up squandering those first three hours reacting to other people’s priorities for us … that ends up using up our best hours and we’re not quite as effective as we could be.”

Studies have shown we experience a decrease in cognitive functioning from morning to afternoon. “With fewer cognitive resources available late in the day, the person performing the task may experience it as more onerous,” write researchers in the Journal of Vocational Behavior. In other words, don’t put off the tough stuff.

It’s also important to be proactive rather than reactive in the first part of your day. “We want to be responsive to our clients, we want to be responsive to our colleagues, but being responsive first thing in the morning is really cognitively expensive,” says Friedman. “It prevents us from leveraging our best hours.”

Think Like a Chef

How best to start your day, then? The culinary world seems to have this strategy down, Friedman believes. The French even have a term for it: mise en place, meaning “everything in its place.”

“If you look at the way that chefs operate, they don’t rush into the kitchen and immediately start cooking. Instead, they very deliberately take time at the beginning to picture the perfect execution of a dish and then they work backwards,” Friedman says. “They identify the steps they need to perform, they select and gather the right tools, they prepare the ingredients in the right proportion, and then they arrange everything they’ll need in their station. So in short, they’re strategizing first, but then they’re executing second.”

Using the first few minutes of your day as a time to plan and put things in order, rather than diving right into work, will help you take a more focused approach throughout the day.

Know when your brain and body need a rest

It’s not just our brains that get fatigued over the course of the day, according to Tony Schwartz, founder of The Energy Project. Physiologically, we follow what Schwartz calls “ultradian rhythms,” or cycles that last 90 to 120 minutes during which our bodies become fatigued and need a break. Think of these as attention-span cycles. Push past your natural cycle without taking a break, and you’ll start seeing diminishing returns, according to Schwartz.

Instead of managing your time, think of managing your energy or attention.

That means not ignoring the telltale signals: feeling restless, yawning, spacing out, or hunger pangs are likely signs you ought to get up and away from your desk for a few minutes. Ignore those signs like many of us often do, Schwartz says, and you’re depleting your energy for the rest of the day.

Manage your 3 p.m. energy dip

You know the feeling — lunch has passed, but the end of the workday is still hours off and you’re pretty much steamrolled. That dip in energy, which typically happens around 3 p.m., coincides with our bodies’ circadian rhythms. Our bodies naturally release a hormone called melatonin and our body temperature drops around this time, which causes us to feel sleepy. If a quick 20-minute nap isn’t in the cards for your workday (though it could be a great option), there are other options.

“Take those fluctuations of energy into account and plan some of the less taxing work, the work that requires less willpower, less concentration [and] focus on doing those types of tasks at 2 or 3 o’clock in the afternoon,” Friedman says. That might mean scheduling a meeting that’s lower down on your priority list during that time or doing the kind of work that doesn’t require as much precision.

This dip in energy might also be a good time to focus on creative tasks. “We’re actually better at being creative when we’re fatigued, which is kind of an interesting and counterintuitive insight,” Friedman says. “Scheduling a creative task for the time in your day when you know you’re a little bit tired can actually be beneficial.”

The imperative word here again is scheduling. Don’t let your day get hijacked by fatigue. Be strategic about how you divvy up your time in advance, and you’ll be prepared to ride the energy dip when it arrives.

Set an end to your workday (and stick to it)

It’s easy to allow our work to extend indefinitely into the rest of our lives — checking email during dinner, before bed, even in the middle of the night. “We work and live with these devices that make everything feel urgent and it’s become neurologically addicting,” Friedman says.

Factoring in time to disconnect can have profound effects on your ability to focus and feel refreshed the following day at work, but prying those shiny glowing gadgets from our hands for hours at a time can feel nearly impossible. One suggestion: Friedman minimizes the temptation to check his email in the evening by using different devices for work and leisure. “I don’t have email on my iPad. So the iPad becomes a device that I use for pleasure, whereas the phone is a work tool,” he says.

Schedule time to play

Play more videogames. That’s right — videogames. According to Friedman, scheduling play into your day is an important way to increase your cognitive function. “Video games get harder the longer we play them. Every board is more difficult,” Friedman says. “In work, it’s often the opposite trajectory. We don’t have that progressive difficulty.”

Exercise is a great option as well. “An increase in physical activity is associated with a decrease in work-related fatigue over time,” write researchers from the Behavioral Science Institute in the Netherlands. But of course, the paradox remains: “Fatigued workers who would benefit most from physical activity, are less physically active.”

The takeaway: get off your butt and do something active, but make sure you’re having fun while you’re at it. Finding that kind of stimulation outside the workplace can be a good reminder that you need to keep challenging yourself at work rather than getting complacent in your role.