1. Exercise won’t work if you don’t start eating better.

“Diet is just as important at fitness,” explains Mac Gambill, a former trainer and a cofounder of the health app Nudge. “Consuming an unhealthy diet counteracts all the effort and dedication of going to the gym.”

2. Your goals are totally unrealistic.

New York–based trainer Dan Flores agrees with Gambill, saying, “People think they can mistreat their bodies—poor eating, drinking, inconsistent exercise—yet be able to pay a personal trainer and magically get results.”

How else are we unrealistic? Flores adds, “I also would like to tell them that they're never going to look like that model in the magazine. Very few people in this world are that good looking … genetics plays a huge role when it comes to that.”

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3. I am not your therapist.

Fitness instructor Kim Mackenzie says, “While I'm all for exorcising those demons through conversation, when you're training with me, you have to actually exercise! Too often I see trainers spending more time on chitchatting with their clients, rather than actually exercising.”

4. No more cheat days!

NASM-certified trainer Chardét Durbin, owner of Brazilian Bootcamp in New York City, says, “It’s OK to have a bad meal, but a whole day of it that you look forward to is quite different. … It is possible to erase a week’s worth of healthy eating with one day of binging.”

“This is never going to work for you because you don't really want it.”

5. It’s not me—it’s you.

ACE-certified physical trainer Austin Arnold says, “Getting healthier, losing weight, and gaining muscle mass are all 100 percent achievable. It is science. Everybody has the ability but the few that are willing to put in the time and effort are the ones who meet their fitness goals … if you don't meet your health and fitness goals, it will be your fault.”

And NASM-certified trainer and nutrition specialist Sarah Bright says, “Unless you're performing an exercise unsafely, I won't call you out personally in a group setting. But I don't make general form announcements just to hear myself talk—someone is doing it wrong, and if you don't think it's you, it probably is.”

6. You have to be your own strongest motivator.

Gambill says, “Trainers are there to help and support people who want to become healthy, fit, and happy. If there is no self-dedication or motivation to work with from the beginning, a trainer cannot [force] a new lifestyle."

Certified personal trainer Wes Ferguson says he wishes he could tell some clients that “this is never going to work for you because you don't really want it.”

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7. There’s no such thing as magic.

Nutritionist and ACE-certified fitness trainer Patricia Greenberg says, “The majority of overweight or out-of-shape people I encounter have tried every diet gimmick available, without success, yet still believe in the ‘miracle.’ … Don't tell me that your sister-in-law’s second cousin lost weight by eating nothing but sunflower seeds. Eating grapefruit doesn’t burn fat. And chewing gum doesn't suppress the appetite.”

She adds, “Fitness professionals work for hours to give you a custom program, and then you arrive and argue that it won’t work or it’s too hard. Yes, it’s hard!”

8. You have to work your whole body.

Jillian Bullock, an ACE-certified group fitness instructor in Pennsylvania, says, “Practically all my clients think you can spot reduce—for example, their stomachs. That's not how it works. … It’s necessary to work the whole body in order to lose fat and build tight, toned muscles.”

And about clients who come to her hoping to look like Jennifer Lopez or Beyoncé, she adds, “They really have no idea how much both of those women train and eat clean in order to get the bodies they have.”

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9. No mercy!

Certified personal trainer and registered yoga teacher Julia Chan says, “I want to tell those clients that consistently complain and whine through the session that it doesn't help them to do so. That is fuel to my fire to get them to work harder and get their heart rate up so they can't say anything at all.”

Trainer Nicole Sanders of Ladimax Sports & Fitness puts it a little more bluntly: “Stop your whining and just get it done!”

10. Your priority should be your health.

Greenberg explains, “You can’t change your body type. If you are shaped like an eggplant, you may need to accept that. If you are honest with yourself, you will be more successful.”

First things first, she adds, “Go to the doctor and get a checkup, it’s futile to guess your cholesterol, blood pressure, diabetes risk, and weight without the numbers.”

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11. I can tell when you’re lying.

Fitness expert Gina Faubert wants you to know that she can tell a lot about your diet and your level of nutrition just by looking at you. She adds, “I can see by the way you’re dying during our workout that you didn’t follow your diet this week” and “You are lying about how many carbs you had this week, I can see it in your waist.”