As a personal trainer for pro athletes, actors and Fortune 500 execs, I’ve been in a lot of gyms in my life. As you can imagine, I’ve seen a ton of training mistakes.

Standing out among the many are the following six egregious—and sometimes dangerous—progress killers. (In addition to squatting too deeply, the guy above is making nos. 3 and 6.)

If you really want to build the body of your dreams, avoid them like the Shake Weight.

“That dude with the huge pecs might look great at the beach… until he steps a few feet into the ocean and his ankles are so weak that the first wave knocks him on his ass.”

1. Spending All Day in the Gym
You don’t have to take up residence there to see results. You don’t even need an hour to see results. The key is intensity. Intensity and diet define results. So it’s much better to go hard for 20 minutes than to go through the motions for an hour. I’m not exaggerating, either. Consider this: in terms of calories burned, 11 minutes of jumping rope is equal to 30 minutes on the treadmill at a moderate jog. You can save yourself a lot of time and get a better workout if you simply commit to a higher level of intensity. Go hard, then go home.

2. Working Only Upper Body
Guys are notorious for neglecting their legs. You see these dudes in the gym who are built like oak trees—big on top, small on bottom (and usually wearing sweatpants to hide it). But think about it: a palm tree has a better chance of surviving a hurricane. To be strong, you have to train your entire body, not just your biceps and your chest. That dude with the huge pecs might look great at the beach… until he steps a few feet into the ocean and his ankles are so weak that the first wave to come by knocks him on his ass. Work your lower half with exercises like squats, lunges and deadlifts. Otherwise you’ll just be phony strong.


3. Using Too Much Weight
Remember why you’re working out: to get healthy in a safe environment, to feel better mentally and physically, and to sculpt a body that’s aesthetically pleasing to yourself, not anybody else. A lot of guys lose sight of these goals, it becomes too much of a contest to see who can lift the most weight, and the first thing that happens is their form goes. Then come the injuries. They overload the Smith machine and pull a hamstring. They overload the leg extension and strain their patellar tendon. They overload the bench press and hurt their back. (Or crush their larynx.) Take it easy. You don’t have to go all Schwarzenegger to get a good workout. To perform an effective squat, for example, you don’t even need weights.

4. Bench-Pressing With Your Feet Up
This is one of the worst things you can do in the gym—maybe in life—and it drives me nuts. I’ve heard every reason, too. “Oh, my back feels safer this way.” It’s not safer. Even if you’re doing 135 pounds, you’re now on an unstable surface. You don’t have anything touching the floor. So what you’re doing is more of a core exercise than anything else. And what happens if you get slightly off balance when you’re pressing the weight? You’re going to dip to one side and have no way of regaining your balance. Now you’re in trouble. You’re going down, and you’re going down hard. Simple solution: keep your feet planted firmly on the floor. It increases balance, support and stability, and it’ll add strength to your bench press. Not one Olympic lifter does any different, and neither should you.

5. Doing Everything on a Stability Ball
Look, stability balls have their place in the gym. They’re great for core exercises. They’re great for rehabilitation or even pre-habilitation, where you’re performing certain exercises to prevent future injury. But too many people overuse them. They think they can use a stability ball to get stronger. But they can’t, because the stability ball does not build strength. You want to build bigger, stronger shoulders? A bigger, stronger chest? Then get on a bench. Because when you sit on a bench, your core is going to be stable and you’re going to be able to better target the muscles you’re actually trying to work. Again, I’m not saying stability balls are worthless. I’m just saying they’re not the cure-all that some people think.

6. Wearing Only Spandex Shorts
Come on, dude, seriously? Put some regular shorts on over the top. This isn’t Europe.

As a top certified strength and conditioning coach, personal trainer and sports nutritionist, Jay Cardiello has helped Hollywood A-Listers, Fortune 500 CEOs and NFL players sculpt the best bodies of their lives. Learn more at