Look man, I’m going to be straight up with you: You’re likely doing it wrong at the gym. Take it from me, someone who until pretty recently (last month) didn’t know anything (okay, I knew a little) about working out at the gym. 
What changed? I met with Edward Jackowski a personal trainer, founder of Exude fitness in New York City, and author of seven books including  “Hold it! You’re Exercising Wrong." Jackowski, who is a master at what he does, examined me with a single look and explained what workout routine I should be doing based off my body type.
When I explained my current workout routine to Jackowski, a collage of exercises I discovered online and through word of mouth, he told me I was doing everything wrong and that I wasn’t alone. 
Here’s what are the three most important things I learned to do at the gym (everything you’re not doing).

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1) The importance of stretching and when you stretch.
More often than not, men aren’t stretching at the gym. If they are stretching, there is a decent chance that they’re not doing it at the right time. Jackowski explained to me that the best order of operations for exercise isn’t to stretch before working out, but to stretch after a proper warm up.
“By warming up and stretching you are asking you body for permission ‘may I be aggressive with it,'” Jackowski explained, which is also a great way to avoid injury or strain to your body. 
A warm-up can be any mild exercise that gets you nice and lubricated with sweat. Whether it’s pedaling on a bike, or jogging on a treadmill until you feel like a human Slip 'N Slide, after seven minutes you’ll be warmed up and ready for a good stretch. 

2) Focus on your core (and when to do it).
Most men do only two things in the gym: lift weights to bulk up their arms and chest, and intimidate me. This is because men, and humans in general, like to do what they’re good at (especially intimidating me). 
What they often leave out of their work out is their core, which Jackowski describes as your lower abdomen, upper legs and groin. It’s a region most men leave out of their routine. 
“Men are good with the crunches, but they're not good with the lower abs,” Jackowski told me as a matter of fact. It’s not just that, however; men often leave this area as the last part of their routine, or dump it all together. 
“When you work out and you save your abs for the last part of your work out, because you lifted so many weights at the end, you lose motivation because you're tired,” And that often leads to an incomplete set, or skipping them altogether, Jackowski emphasized.    
The lesson? Do your core workout immediately after you stretch. Core workouts suck, but it's best to get the worst out of the way first.
3) Lifting too much weight (boy, you’re gonna carry that weight).
One of the most intimidating aspects of the gym are all the gorilla bros lifting small school buses over and over and spewing testosterone like it’s no one’s business.
But does your fitness routine really need you to lift your first grade class’ collective body weight over and over again?
“The reality of the situation is that we don’t need to be lifting that much weight to receive the benefit,” Jackowski told me, which was a relief for my toothpick arms and weak work ethic. 
What Jackowski explained to me is that higher reps with a more moderate amount of weight will help you both burn calories as well as tone the muscles in your body. So if your goal is to look not-hideous when you take your shirt off (that is everyone's goal), then this is honestly the route to take. 

Matt Lee is a Web producer for Metro New York. He writes about almost everything and anything. Talk to him (or yell at him) on Twitter so he doesn’t feel lonely @mattlee2669.