Are You Following Proper Gym Etiquette?

She has, like, so much to catch up on with her friend—on her cell. Though many gyms have enacted cell phone bans, people still feel compelled to answer them midworkout.

Best defense: If cranking up your music can't tune her out, or if she's a habitual offender and it's really affecting your workout (you can't concentrate, or you're pissed), don't confront her—that could escalate a situation. Tell the staff, who will handle it, advises Stephen LoCicero, the personal training manager for Blink Fitness in New York City.

She sneezes, then picks up weights; the next treadmill over, he's hacking up a lung. Touching the germ-covered equipment and then your face can transfer their cold or flu viruses to you. And you're more at risk now, as studies show that high-intensity exercise, like speedy running, stresses your body and temporarily lowers your immunity.

Best defense: Bring your own towel to wipe down equipment. Mark one side with an X in permanent marker to designate the dirty side, says fitness pro Marta Montenegro, an adjuncy exercise physiology professor at Florida International University. And don't be afraid to ask germy gym-mates to wipe down their own machines. Better yet, politely ask a gym staffer on the floor to tell them to do it.

Related: How to Deal with Germs at the Gym

Obviously, leaving your tech or treasure in an unlocked locker or out in the open creates a welcoming environment for theft, according to Lori Pines, the author of The Little Book of Gym Etiquette. "Stealing is largely a crime of opportunity," LoCicero says.

Best defense: Leave valuables at home if possible, LoCicero suggests. Lock your things up every time. If you forget your lock, ask the front desk to loan you one (there might be a small fee, but it's worth it). If a loaner isn't available, keep small valuables next to you while you work out, as long as they don't create a hazard. Many gyms offer small lockboxes for stashing jewelry, wallets and cell phones.

Not having anywhere to put your stuff while getting ready because someone else is taking up the entire bench "can leave you seething when you're supposed to be de-stressing," Pines says. "That's not a note you want to start or end a workout on." Plus, it makes it just plain difficult to get dressed yourself.

Best defense: Read the situation. If the person seems like she's rushed or tense, wait for her to leave rather than ruffle her further with a request to make some space, Pines advises. "Otherwise, politely ask her to scooch her stuff over. Try 'Hey, can you make a bit of space for me? I'm not talented enough to put my shoes and socks on while standing,'" Pines says.

Unless you're into it too, the guy whose eyes are planted on your butt whle you lunge and squat is, at best, a distraction. At worst, his creeptasticness can make you dread going to the gym.

Best defense: "You know what intimidates men? When women work out hard," Monteegro says. "When I'm so focused on my technique, I look so serious and tough that I think I scare them off." Bonus: Pumping up the intensity torches more calories. But if you're majorly skeeved out, alert a staff member who will speak to the leering dude in private, says David Walker, a regional manager for Planet Fitness. That way, you don't risk confrontation.

When a trainer swings by to correct you ("Did you know you're doing that wrong?" "You should try a heavier weight!"), he may have the best intentions, but he doesn't know your body or background. "If someone hasn't taken a proper assessment of you first, you don't need to automatically take his word for what you should be doing better, say Jessi Kneeland, a personal trainer for Peak Performance in New York City.

Best defense: Listen with an open mind and say thank you—the advice could end up being helpful if you're trying something new. Otherwise, explain that you've got your own way of doing the exercise, turn around and get back into your groove, Kneeland suggests.

They've got an entire circuit set up: dumbbells, a stability ball, a bench and that medicine ball that's your perfect weight. You've got nothing. If you can't find the right stuff for your workout, your session can end up being less effective, Kneeland say.

Best defense: When someone is resting and obviously not using the equipment, that's the perfect time to ask if you can "work in" with him or her. Or, try a Plan B. All the ellipticals taken? Look at it as an opportunity to try something new, like the rowing machine (we like this plan). You'll work different muscles and switch up yor regular routine—not a bad thing.

A word to the exhibitionists: "Do we really need to see you bend over and blow-dry your hair while naked? Or worse, see you sit on a bench with your bare butt?" Pines asks.

Best defense: Make light of the situation (while getting your point across) and jokingly ask, "What's with the excessive nakedness?" Pines suggests. If that's too awkward, then you'll have to ignore her. Focus on what you're doing to tune out everyone else and get on your way quickly.

You're feeling all cool, calm and collected in savasana at the end of a mind-clearing yoga class and—bam!—someone ruins the mood by rolling up her mat and stomping across the room and out the door. "As class starts, we often stress the benefits of staying the entire time," says Jeni Hutchison, an instructor and regional manager for CorePower Yoga in Chicago.

Best defense: Hutchison recommends using the same techniques that you use during class to bring back a wandering mind: Focus your attention on your breath—how it sounds, what it feels like—or repeat a mantra, like "calm and strong." We can all relate to leaving early sometimes, but if it becomes a consistent distraction, you should bring it to your instructor's attention. Need to bounce early yourself? Clue in the instructor before class, set up in the back by the door and scoot quietly, ideally during a transition (like a drink break), Hutchison says.

She waltzes into Zumba and positions herself directly in front of you so you're clueless to the instructor's physical cues. "Seeing the instructor is important, because it helps ensure you're doing the moves correctly," says Greg Corso, a trainer at Sports Club/LA in Miami.

Best defense: Sure, you can ask her to move over, but in crowded classes there may be no way around your view being blocked by others. In that case, try moving yourself if there's space, or watch a class regular and mirror her, Corso says. And you probably know which classes will be mobbed (those before and after work hours, for example). Try to get to crowded classes early to guarantee a good spot on the floor, he adds.