Fitness facts you might not know that will boost your workout . . . or encourage you to start

There is rarely enough time in the day to accomplish everything we set out to do, and exercise is often sacrificed when time is short. Guidelines Recommend Include 2½ hours of moderate physical activity in our lives each week, and make time for muscle-strengthening exercises.

Sometimes I find this guide overwhelming, and I am not alone. So I was interested in the research: how much physical activity does a person need to live longer and reduce the risk of chronic diseases? How often do they really need to exercise?

Exploring the science and talking to researchers yielded some surprising insights, such as that you don’t need to exercise every day and that stretching doesn’t automatically prevent injury.

Here are research-based ideas that can make you more excited to exercise.

You can keep workouts short

Ireland’s National Physical Activity Guidelines recommend “at least 30 minutes a day of moderate-intensity activity, five days a week (or 150 minutes a week)”. Still, you can benefit from doing less, says Dr. I-Min Lee, a public health researcher who studies exercise at Brigham and Women’s Hospital in Boston.

The first 20 minutes of physical activity per session confers the most health benefits, at least in terms of longevity, says Dr. Lee. As he continues to exercise, “his return on investment starts to decline” in terms of tangible health rewards, he adds.

But what if you only have five or ten minutes to exercise? Do it.

“There’s a lot going on in your body from the moment you start exercising,” says Carol Ewing Garber, a movement scientist at Columbia University Teachers College. And it’s possible to experience mental health benefits, including reduced anxiety and better sleep, right after moderate to vigorous physical activity.

no need for intensity

If high-intensity interval training and intense spin classes make you want to hide, don’t worry. You don’t have to sweat profusely or feel gutted after a workout to reap some rewards.

Any physical activity that makes your heart beat a little faster is helpful. If you’ve never monitored your heartbeat while exercising, it might be worth a try. For moderate exercise, the recommended goal is about 50 to 70 percent of your body’s maximum heart rate. (To calculate your maximum heart rate, subtract your age from 220.) Many people will reach this goal during a brisk walk, says Beth Lewis, a sports and exercise physiologist at the University of Minnesota.

Estimating your maximum heart rate can help you gauge how hard you should walk, run, or bike. But it’s not perfect, as your natural heart rate during exercise may be higher or lower. Also, fitness levels and heart rates among people of the same age can vary, and not all exercises increase heart rate by the same amount. Consider talking to your doctor before setting your goals. “Just moving your body in some way will help,” says Garber. “That’s a really important message.”

Focus on health, not weight loss

Many people exercise with weight loss in mind, but simply increasing physical activity is often not effective. In a 2011 review of 14 published articles, scientists found that people with larger bodies who did aerobic exercise for at least two hours a week lost an average of just 3.5 pounds in six months. And in a small clinical trial from 2018, women who did high-intensity circuit training three times a week saw no significant weight loss after eight weeks. (They did gain muscle, though.)

Exercise improves overall health, and studies suggest it has a greater effect on life expectancy than body type. Regardless of your size, exercise lowers your risk of heart disease, some cancers, depression, type 2 diabetes, anxiety and insomnia, says Lewis.

Weekend-only routines are fine

I’ve always assumed that the healthiest athletes exercise almost every day, but research suggests otherwise. In a study published last month, researchers followed more than 350,000 healthy adults for an average of more than 10 years. They found that people who exercised at least 150 minutes a week, for one or two days, were no more likely to die for any reason than those who got to 150 minutes in shorter sessions. Other studies by Dr. Lee and her colleagues have come to similar conclusions. When it comes to the possibility of living longer, “it’s really the total amount of activity per week that’s important,” says Dr. Lee. But, he adds, if you exercise more often, you’re less likely to get injured.

stretching is optional

Recommendations to stretch before and after workouts annoy me, especially if I’m pressed for time. But research suggests stretching doesn’t actually reduce injury risk. “It used to be a required part of what you do: ‘If you don’t stretch, you’re going to hurt yourself,'” says Lewis. “That mentality is wrong.”

Instead of static stretches, such as touching your toes, Lewis recommends doing dynamic stretches before exercising, such as gently rocking each leg back and forth while standing. However, static stretching can help increase muscle flexibility and joint mobility, she explained. But now I know not to worry if I don’t have time to do it. — This article originally appeared on the New York Times