Three-day weekends are a leisure until they turn into four-day weeks with five days' worth of work. Even during a full week, you may feel that your work is never done, especially as entrepreneurship becomes increasingly synonymous with constant work. There is little to say, however, that the more time you spend working, the more you get done. In fact, a recent Stanford research study found that our output actually decreases after a certain threshold (56 hours a week).

Put another way, working hard and smart is actually about working less. Here are four ways to make the most of your work hours without making more work hours.

1. Time-box your work.

English novelist Anthony Trollope maintained a strict writing schedule while also pursuing a "day job." Each morning, he read his previous day's work for thirty minutes starting at 5:00 AM. He then placed a watch on his desk and time-boxed his writing to two-and-a-half hours, after which he left for his office. Completing 1000 words an hour and 40 pages a week, Trollope published 47 novels before he died at the age of 67. He wrote, "All those I think who have lived as literary men,--working daily as literary laborers--will agree with me that three hours a day will produce as much as a man ought to write."

While a three-hour-workday may be drastic, setting a strict daily timeline is not. Define what you need, and specify how long you'll need to do it. Keep yourself honest about staying within the time-box.

2. Define your on-season and off-season.

During the NBA off-season, Kobe Bryant followed a "666 schedule"--six hours of training each day, six times a week, for six months. This provided balance to the NBA season, which is notoriously strenuous. Teams are constantly on the road (or in the air), often arriving at their hotels late into the night and needing to be on the court early the next day. This schedule is physically taxing and takes a toll on the body--no matter how in shape you are. The off-season enables athletes to train for the following season while also recuperating from the intensity of the previous season.

Every organization has intense periods, especially around big milestones like public events, product launches, and important meetings. It's important to remember, however, that intense periods must come to an end (or pause) frequently. Perpetual overdrive is unsustainable. Try to identify and plan for peaks in your fiscal year--then ensure that each one is paired with rest moments.

3. Schedule leisure time.

Charles Darwin famously followed a daily routine that involved serious work and serious leisure time. After working from 8 AM to 9:30, he read his morning mail and answered letters until 10:30 AM, then went back to his work until noon. At this point, he would declare, "I've done a good day's work." He went on an hour-long (or more) walk on a path around his property called the Sandwalk, then returned to eat lunch, answer more letters, and nap until 5:30 PM when he joined his family for dinner. With this schedule, Darwin wrote nineteen books including The Origin of Species.

Leisure time does not need to be a weekend luxury. Find ways to build restorative moments into your day, whether it's going for a lunchtime walk, cooking a nice meal, or spending time on a hobby before or after work.

4. Prioritize sleep.

Indra Nooyi, Jeff Bezos, Tim Cook, Jack Dorsey, and Arianna Huffington all sleep seven hours each night -- all while leading large, successful organizations. One study showed that insufficient sleep (defined as less than six hours each night) is a key predictor of on-the-job burnout. Further, a Harvard study estimated that sleep deprivation costs American companies $63.2B in lost productivity annually.

To prioritize your work, prioritize sleep. Try to go to bed and wake up at the same time each night, and strive to get at least six hours of sleep.

Sometimes, it can feel like achieving work-life balance is more difficult than the work itself. You'll find however that the extra effort to do so will save you invaluable effort in the long run.