Everyone wants to be more productive. Even if you're not someone who chases the latest productivity trend, there's a pretty good chance that you'd like to be able to get more done without having to spend more time working. Of course, we all get the exact same amount of time, so the traditional approach has been to figure out the best way to use your time to get the most done. 

That's why a lot of productivity tips have to do with managing your time. The idea, I suppose, is that if you could just better organize the tasks you have to accomplish on your calendar, you'll be able to do more of them. 

Certainly, it's true that how you spend your time is important. It's also true that many people aren't as efficient with their time as they could be. But only focusing on how you manage your time misses a larger point, and it's one that's backed by science.

In an interview with McKinsey & Company in 2013, then Ford CEO Allan Mulally was asked about maintaining mental and physical stamina. His response was interesting because it had little to do with how to fit more things on a calendar.

Everybody always talks about how you need to manage your time. You need to manage your energy as well. You first have to ask, 'What gives me energy?' There can be lots of sources: your family, exercise, your spiritual well-being.

There is a lot of great insight in that quote, but I think the most helpful is the idea that you should "manage your energy." Mulally suggests that it's something you should do "as well," implying that both are important. I think that's true, but I think that managing your energy is far more important overall, and the science backs that up.

A 2008 article from Harvard Business Review explains: 

The core problem with working longer hours is that time is a finite resource. Energy is a different story. Defined in physics as the capacity to work, energy comes from four main wellsprings in human beings: the body, emotions, mind, and spirit. In each, energy can be systematically expanded and regularly renewed by establishing specific rituals--behaviors that are intentionally practiced and precisely scheduled, with the goal of making them unconscious and automatic as quickly as possible.

The idea is that the key to getting things done is to manage your energy. According to the authors, you do that by creating habits and being intentional about the things that give you energy. Over time, as you build those habits into your routine, they become a source of energy. In turn, that helps you be more productive. 

The reason is really quite simple. The problem with being productive isn't that you don't have enough time. The problem is that you probably spend most of your time on things that drain you of energy. The way to be more productive isn't to cram more into your schedule, but to make sure that you look at your time as an investment.

If you invest it well, you get a positive return on your energy, which gives you motivation and an expanded capacity to be productive. For example, the HBR article says that individuals "need to recognize the costs of energy-depleting behaviors and then take responsibility for changing them." 

HBR came to that conclusion after working with employees at 12 regional banks. The employees who participated in a series of modules designed to help them focus on what gives them energy turned out to be more productive at work, delivering better performance than individuals who hadn't participated. 

As Mulally mentions, that might look different for everyone. For example, the things you eat contribute to your energy level. So does whether you got enough sleep. Doing things that make you happy, or things for which you have a passion, give you energy.

For some people, going for a walk in the morning might give them energy and help them start the day with motivation. For others, the same might be true for having breakfast with their family before leaving the house. Maybe it's coaching your son's baseball team.

Sure, these things take time, but the return on your investment of time goes far beyond the 30 minutes you spend riding your bike, or the hour of chasing after foul balls. If those activities give you energy, you can then funnel it into other areas of your life, like your work.

By the way, it's quite possible that your work gives you energy. If so, you're very fortunate. Even still, it's important to recognize what it is about the work you do that revitalizes and motivates you so you can be intentional about building it into your routine. 

There's also a lesson here for managers, which is that this isn't just about you. If you manage people, you can help them be more productive by helping them better manage their energy. In fact, I'd argue that it's your responsibility to give your team everything it needs for success. Sometimes that's as simple as giving them the freedom to figure out the answer to the question "What gives you energy?"