Sometimes a work mistake can have dire consequences. Maybe you didn't finish a project in time and your company lost an account, or perhaps you made a poor decision that caused someone to lose his or her job.

In many cases, though, our bad work decisions aren't quite so grand. Instead, it's a small thing we do wrong a lot that has consequences that build over time. That can affect our own careers, damage our physical well-being, or harm our company.

On the positive side, these are things we can fix easily. Heading into the new year, you can resolve to not repeat the mistakes of the past year. That's not always easy, but sometimes undertaking small changes or just being willing to make an effort can pay off enormously. Here are some tips from three of our Foolish investors.

A tired woman sits with her hand on her head at a laptop.

Not taking care of ourselves is a common work mistake. Image source: Getty Images.

Trying to power through the day

Maurie Backman: Even if you enjoy your job, and are pretty efficient at getting it done, there comes a point during any given workday when you just plain need a break. Earlier this year, I was intent on meeting certain deadlines, several of which were self-imposed, and so I got into the habit of working long stretches at a time without stopping for a rest. And while I didn't mind not getting a break, I did find that my work began to suffer.

At one point, for example, I came close to submitting an article with a clearly botched calculation that would've confused the heck out of readers and made me look downright stupid. (Imagine a personal-finance writer who can't do basic math.) And the reason for that error boiled down to not taking a step back and giving myself a chance to see things clearly.

These days, I make a point of taking a break after every couple of hours I sit writing. This way, I'm approaching my work from a fresh perspective, and am less likely to make errors for the world to see.

While it's a good idea for all workers to take regular breaks during the day, it's especially crucial if you're doing something creative, or something that requires major concentration. In fact, several studies have shown that working fewer hours can increase productivity, so if you feel guilty about taking those breaks, that's a good reason to change your line of thinking and start stepping away from your desk more often.

Never taking time off

Daniel B. Kline: Unlike Maurie, I'm pretty good at taking breaks during the day. I'm lucky enough to live in West Palm Beach with a pool only an elevator ride away, so on most days I take a swim to break up my work.

What I'm not very good at it is allowing myself to take extended time off. The problem is that as a self-employed writer, my income is tied to my output. Taking a week or even a few days off means I don't make any money that week, which can make a vacation less enjoyable.

There are ways around this problem. In 2018, I plan to track my income over months and even quarters. As long as I hit my goals for those longer periods, I'm going to try to put less focus on how much I make each day and week.

I'm putting this plan to the test in January, when I'm heading out on a cruise. Since my trip will be over the New Year's holiday, I'm only missing three full days of work, but it's a start, and the early month vacation should leave me plenty of time to catch up on the income lost.

Hopefully, in 2018 I'll take at least one more extended break, maybe even a full week off. I know that will ultimately make my work stronger and give me a chance to recharge my batteries fully.

Not tending to my health

Selena Maranjian: A work mistake I made in 2017 is one I've made in many years, and one that can be very costly: not tending to my health. For example, most of us know that we should be eating nutritious meals and not overeating. But that can be hard to do if you work in an office chock-full of opportunities to eat poorly -- such as pizza lunches once a week and break rooms stocked with chips or cookies -- or if you work from home, with a well-stocked refrigerator and snack cupboard just a room or two away.

Sleep is something else that's vital to our health, and it's rather underappreciated, too. According to the National Institutes of Health, "Sleep deficiency is linked to many chronic health problems, including heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity, and depression." It's also associated with greater risk of injuries, mistakes, and accidents. If you want to think as clearly and effectively as possible while on the job, don't underestimate the value of getting enough sleep. I know that I often get less sleep than I need.

As Dan and Maurie pointed out, it's also important to take breaks -- short breaks during the day and longer multi-day breaks during the year. According to a recent Forbes article, Americans are increasingly choosing work over leisure. Supporting that, the U.S. Travel Association found that in 2016, American workers left a record-setting 662 million vacation days unused. Meanwhile, various studies are reporting that sitting too much can shorten your life. According to one, "[T]hose who sat for more than 13 hours per day had a two-fold (or 200%) greater risk of death compared to those who sat for less than about 11 hours per day."

I know I need to focus on my health more. Maybe you do, too?

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