We’re busting the most common exercise myths right here so you can reach your fitness goals.

There’s no shortage of fitness programs promising fast (and unbelievable) results. Yeah, we wish we could get six-pack abs in five minutes too. But the truth is these exercise myths just don’t work. In fact, they could actually get in the way of your get-fit goals. “Without the right information, you could spend your time and energy doing things that won’t help you get results,” says Aimee Nicotera, a fitness and nutrition expert in St. Petersburg, Florida, and the creator of the Take 20! and 2×2 Conditioning DVDs.

Nicotera is here to help you out by debunking four common exercise myths and sharing what you can do instead to get the most out of your workouts.

Myth 1: You have to exercise for at least 30 minutes at a time or it’s not worth it.

Why it’s not true: “Anything is better than nothing, even if that means just taking a five-minute walk,” Nicotera says. As soon as you switch into active mode your body starts burning fat, which is why any amount of huffing and puffing is time well spent. And if you can find a few minutes at different times each day to get out of your chair and move, all the better. Sounds doable, yes? In fact, take enough exercise breaks each day and you’ll be doing your body just as much good as if you put it through one longer, continuous workout.

Try this instead: Make the most of what time you do have by aiming for fairly intense exercise—something that will leave you feeling tired and breathing harder than when you started. We like the idea of breaking up the workday with quick rounds up and down the office stairs a couple times a day or with brisk laps around the block before lunch and dinner. But that’s just us. Put some thought into things that seem reasonable for your schedule and surroundings and, well, just do them. The rule of thumb for your daily exercise total remains 30 minutes, so use that as your target.

Myth 2: Crunches are the best exercise for a stronger core.

Why it’s not true: Don’t you love it when mandates you loathe actually get scrapped? (Come on, no one looks forward to doing sit-ups.) That’s why we were thrilled when Nicotera clued us in to this gem of an exercise truth: The best way to shore up your midsection is to work your muscles the same way you do in daily life, and “crunches don’t mimic anything you do in everyday activities,” Nicotera says. Plus, exercises that stimulate the most muscles challenge both balance and mobility, which crunches don’t do.

Try this instead: Just because crunches aren’t all they’re cracked up to be doesn’t mean we’re off the exercise hook. (Sorry to disappoint.) But at least the alternatives are more palatable. Nicotera directed us toward standing balance work—like touching the floor while balancing on one leg—as one of the best ways to develop core strength. You can also do planks (holding a push-up position but with your weight on your forearms instead of your hands) for 30 to 60 seconds at a time.

Myth 3: Cardio is the only way to burn fat.

Why it’s not true: Heart-pumping activities like a Zumba class or power walks are great for burning fat. But you’re shortchanging yourself if you only do cardio. “Not only might you increase injury risk, you’re also not building lean muscle, which helps you burn more calories,” Nicotera says. The way to build muscle? Strength train.

Try this instead: Aim to log two or three strength workouts a week, using tools like dumbbells, resistance bands, or even your own body weight. Then try to do five days of aerobic activity, changing not only the type of activity but also the intensity. “Your body adapts quickly to whatever you’re doing, which is why you have to challenge yourself if you want to see changes,” Nicotera says. Don’t worry if this is starting to sound daunting, we understand the appeal of embracing a simple one-trick routine. But coming up with a mixed bag of activities takes more thought than effort. For starters, think of workouts in terms of super hard, hard, and somewhat hard— that’s what it means to switch up the intensity. Next, plug in different activities for each day of the week (making sure you’ve got your intensity bases covered, of course) and, voilà, you’ve found yourself a well-rounded routine. The bonus? By mixing things up, you’ll prevent boredom.

Myth 4: You should stretch before exercise to warm up your muscles.

Why it’s not true: If you do isometric, or held, stretches on cold muscles, you could injure yourself. “Before exercise you want to increase your body’s core temperature and bring the heart rate up gradually, which you undo when you stop and hold a static stretch,” Nicotera says.

Try this instead: Opt for a light aerobic warm-up like a slow jog or walk. Then perform dynamic stretches like knee lifts, which pair motion with movements that require a little flexibility. This way, your heart rate is elevated and your muscles are warmed up before you begin your workout. After your workout, you can cool down with those familiar isometric stretches.