I love this article, written by Beachbody’s Blog writer, Julie Stewart. I especially love mistake #2. I have often wondered why I see so many in gyms with that hunched posture. Lifting weights, when done properly, should IMPROVE your posture!

“It doesn’t matter if you’ve been working out for a week or a decade—odds are you’re making a handful of common mistakes that are holding you back. We’re also willing to bet that most of them aren’t your fault—gyms, exercise communities, and even some popular fitness programs are rife with well-intended advice that’s rooted more in bro-science than real-world research. That ends today. Purge the following mistakes from your training program to accelerate your gains and squeeze out of every rep.

Mistake #1: You stick to a routine
The rapid gains you enjoy at the beginning of a training program will eventually taper if you keep doing the same workouts month after month (or year after year). “The body adapts to new stresses quickly,” says Yunus Barisik, C.S.C.S., author of the blog Next Level Athletics. Your job—and the goal of any good exercise plan—is to make sure that adaptation (also known as muscle growth) never stops. “And the way to do that is by regularly varying what you do,” says Barisik.

The fix: If you’re a beginner, mix things up every two to three months. If you’re a veteran, you’ll need to do so even sooner. “Those changes don’t have to be major,” says Barisik. Occasionally swapping new exercises into your workouts (or trying a completely new workout program) is a smart idea. “But even minor tweaks—changing your grip, lifting pace, foot position, or rest periods—can lead to big gains by not only working muscles you normally miss, but also working the muscles you normally target in new ways,” says Barisk.

Mistake #2: You forget about your back
In their pursuit of head turning muscle, many people focus only on those they can see in the mirror—pecs, shoulders, arms, and abs. “And that’s a problem,” says Barisik. “Overemphasizing the front side of your body can lead to muscular imbalances, a hunched posture, and an increased risk of injury.” Since most people are already “anterior dominant”—meaning they more frequently use the muscles on the front of their bodies—such one-sided training often worsens existing postural and performance issues.

The fix: Stop using a mirror to gauge your progress—it’s the muscles you can’t see that you should focus on. To balance your upper body, perform two pulling exercises (chinup, row) for every pushing exercise, such as the overhead press or bench press, says Barisik. To balance your lower body, perform two sets of hamstring-dominant exercises, like the deadlift or kettlebell swing, for every set of a quad-dominant exercise, like the squat or lunge. After a few months (read: once your posture and musculature balance out), you can switch to one-to-one ratios, says Barisik.

Mistake #3: You train too hard (or not hard enough)
More isn’t always better when it comes to building strength and losing fat. “Most people don’t know how to safely push their limits,” says Michael Wood, C.S.C.S., Chief Fitness Officer of Koko FitClub. “You might think you’re working out efficiently, but few people actually optimize their training stimulus.” While you need to challenge your muscles to make them grow, you never want to push them to the point where you inhibit their ability to repair themselves. Why? Because when it comes to muscle, repair equals growth. On the other hand, if you don’t push your muscles hard enough, you won’t trigger growth at all. Your goal: To hit the intensity sweet spot where you maximize results without compromising recovery.

The Fix: If you’re lifting weights, always stop two reps short of in your last set of an exercise. Those reps provide no additional growth stimulus, and might actually slow muscle growth by extending the time needed for recovery. That said, you shouldn’t have more than two reps left in you, as that’s a sign you aren’t pushing hard enough. If you’re doing intervals or circuits, use a heart rate monitor to fine-tune effort and rest. Determine your max HR by multiplying your age by .7 and subtracting that number from 208. During work periods, build up your intensity to 75 to 85 percent of your max, says Wood. During rest periods, let it fall to 65 percent of your max HR before beginning your next round.

Mistake #4: You don’t dial in your diet
You’ve likely heard the adage “You can’t outrun a bad diet.” It’s true, so heed it. If your eating habits aren’t aligned with your fitness goals, you’ll never hit them. “Many active people eat too many carbs—especially simple carbs like sugar—and don’t pay nearly enough attention to fat and protein,” says Bob Seebohar, M.S., R.D., CSSD, C.S.C.S., a sport dietitian and owner and founder of eNRG Performance.

The fix: Step one in upgrading your diet is to reduce your consumption of added sugar (according to the government’s new Dietary Guidelines for Americans, such foods should comprise no more than 10 percent of your diet). Eat at least two servings of fruit and two servings of vegetables a day. “And make sure every meal contains a balance of protein, fat, and fiber,” says Seebohar. “Neglecting these suggestions will yield poor blood sugar control, higher insulin levels, increased fat storage, and decreased fat burning.” Increasing your protein intake is particularly important. In a study by the U.S. Military Nutrition Division, people who ate twice the recommended dietary allowance (RDA) of protein—1.6 grams instead of .8 grams per kilogram of bodyweight—preserved more muscle as they lost weight than those who stuck to the RDA. If you weigh 150 pounds, your daily protein quota is 109 grams.”