The gym seems like a great place to meet a potential life partner or new BFF -- after all, you know you have at least one common interest. But trying to strike up a conversation with someone who is working out should be punishable by a half-hour set of burpees. "Do I really need to know how much some dude had to drink the night before?" asks personal trainer Shane McLean.

"Most people hate working out and do so for health reasons, so they're understandably focused on themselves," says celebrity trainer Joey Thurman. "Don't try to strike up a conversation with someone wearing headphones."

Meaning: Leave your cell phone in your gym bag. "When I am at the gym I am there to get my sweat on, get pumped up for the day and feel great about myself. Get off the phone and take the time to focus on your workout," says personal trainer Courtney Violet Bentley.

The more the sweat, the better the workout -- that's the general rule. But not for the person who has to enter the swamp-like situation you've created. "My biggest pet peeve is people, men in particular, who sweat profusely and don't wipe their sweat after using a machine or bench," says Bobbi Leder, author of "The Secret Police Dog." "It's unsanitary, disgusting and just plain rude for the next person who wants to use that piece of equipment."

When you take on more weight than you can handle, you're more likely to elicit eye rolls than applause from trainers. "If people are staring, it's not because they think you're cool," Thurman says.

"People will moan, grunt, and even fart a few times before they get a full rep," says Donovan Green, celebrity fitness trainer and author of "No Excuses Fitness." Which turns out, is all for nothing. "They'll either get no benefit or they'll hurt themselves," says Michael Spitzer, author of "Fitness at 40, 50, 60 and Beyond."

A not-so-secret side effect of going to the gym regularly is looking good -- but please keep your rippling physique to yourself. "Whenever I'm in the gym doing my beast-mode workout, I always see a guy who cannot stop staring at himself in the mirror," Green says. "It's like he is getting ready to ask himself out on a date."

McLean says that he especially can't stand guys who pull up their T- shirts to look at their abs like nobody is around. "Dude, the gym is full of people," he says.