I grew up always hearing the phrase, “No pain, no gain!” It was often repeated by my various burly gym teachers, and we were taught to believe that when it came to physical fitness, a little pain was to be expected.

And then as I reached adulthood, that saying was declared a myth by many experts. Oh, fitness shouldn’t be difficult, they said in soothing voices, fitness can be achieved with minimal effort! They offered lists of tips for easy weight loss that were promoted in every women’s magazine – actions that would supposedly add up fast without even noticing. Take the stairs instead of the elevator! Park further back in the parking lot! Walk a little more! It sounded too good to be true.

It is too good to be true.

“No pain, no gain” is not a myth, and anyone who says otherwise is selling something.

I’m going to be totally honest with you, and this is coming from someone who has gained and lost A LOT of weight over the years. Getting in shape, and remaining fit, takes a lot of effort, a lot of sweat, and probably a decent amount of minor pain, too.

Note: I’m not talking about being “skinny” here. Some people are born with amazingly fast metabolisms and it really is no effort for them to remain thin. Yes, I’m jealous. But it’s very possible to be thin and unfit. Heart disease, malnutrition, poor bone density and low muscle tone are not limited to the overweight or elderly.

Our bodies are brilliantly designed to be fat. Thousands of years of evolution have created a body that works very hard to be efficient with every calorie. Modern society may have created the deep-fried Twinkie, supermarkets with abundant calorie-laden foods and drive-thrus on every other corner, but our bodies are still convinced that our food supply might run out at any minute.

It’s why our bodies store fat instead of using only what is needed and getting rid of the remainder in the toilet. Our bodies are preparing for a famine, and would really prefer if we didn’t have to move around so much to make it easier to store up energy for when we’re out of food. Or when we need the energy to run for our lives from something trying to eat us.

Modern society has also proven Newton’s First Law that a body at rest tends to remain at rest. Inertia is a bitch. Recliners, cushy sofas, TV, video games – they all contribute to keeping us at rest. I love my technology as much as the next geek, but just like our food supply, technology has advanced faster than evolution so that the bulk of our work doesn’t require physical labor.

Washing machines and dryers take care of our clothing for us, cars take us between locations, and a large number of workers push a computer mouse instead of a plow or heavy machinery. The day they invent the self-propelled grocery cart is the day my ass gains another inch. (Oh, but wait! I can order my groceries online and have them delivered to my door now!)

BUT! – and here’s the good news you won’t find in a “Lose Weight While You Sleep!” article in some trash magazine – our bodies are also brilliantly designed to adapt to physical stress. We all have amazing athletes hiding inside of us. The human body will re-form itself to meet the challenges around it. Even late in life, the body can still build muscle. The heart can fine-tune its performance to work better. The lungs can be taught to more effectively handle the oxygen exchange. And our brains can learn new patterns of behavior.

OK, now for the bad news: in order to become fit, we have to fight on two fronts. First, we have to fight against the body’s desire to remain at rest. And second, we have to fight the society we have built that encourages us to stay inactive.

The worse news: there will be pain.

It’s impossible to tell someone that they can improve their health and get fit with no pain. I’ve tried practically every “easy” way to lose weight and shape up, and I can tell you they don’t work. Sure, there are pills to lower your cholesterol, lower your blood pressure, make you lose weight, and even help men get an erection. But those pills can’t do all the work for you.

If you want to improve your cardiovascular health, you have to exercise, and it has to be enough to put stress on your system. Stressing your system is not comfortable: your heart pounds, your lungs ache from needing more oxygen to meet the increased demand, your muscles feel weak, you may even feel lightheaded. BUT THAT’S HOW YOUR BODY CHANGES.

If it were easy, your body wouldn’t need to adapt, because it can handle what you’re throwing at it just fine, thank you.

It’s when you’re suddenly running down the street – when you’ve only ever walked before now – that your body is all WTF? WHAT ARE YOU DOING? HEY, STOP THAT, I CAN’T KEEP UP! Whether it’s a little bit of stress or a lot, the body is still injured. Lactic acid builds up in your body from this new exercise, small tears are created in your muscles from working them harder than normal, and your brain then has to figure out what the hell just happened and how to keep it from happening again.

This often hurts, at least a little. The amount of microdamage you do to your body will determine how much it hurts, but you will likely ache. (Note: sharp or severe pain is NOT a good pain – don’t aim for that!) A good ache, though, tells you that you pushed your body outside of its comfort zone, and now it is forced to react.

So your body works to clear the lactic acid out of your system. Nutrients in your food are converted and put to work mending the torn muscle fibers and refilling glycogen stores. But your body is smart – if your exercise caused this damage, then by god it’s going to build a better muscle to prevent this from happening again should you need to run down the street sometime soon. So it repairs the damage and adds an extra layer of amino acid mortar and muscle fiber, just to be safe.

You blow down the straw house, the body builds one of sticks. You knock down the stick house, it goes to bricks. You tear through the bricks, it builds a double wall of bricks with a steel door and a guard dog with an attitude waiting inside. (Wait, I just lost my Three Little Pigs analogy. Well, you get the idea.)

And that’s how it works. You continue gradually pushing your body outside of its comfort zone, and it changes and adapts, hoping you’ll cut it out and stop making it work so damn hard. Eventually you reach your ideal level of fitness, and you need only maintain at that point. But remember that given the choice, your body would love to snack on those deep fried Twinkies and watch TV in the recliner all day. If it thinks it no longer needs that extra muscle, it’ll get rid of it, since muscle requires a lot of energy to maintain.

Your work is not over. There’s one more type of pain you have to endure: mental pain. It’s hard to force yourself to change your habits when the way you’ve done things before is so much easier and more pleasant. I’m still fighting it on a daily basis. I feel that twinge of sadness as I eat my broccoli, knowing a pint of ice cream would taste even better. Convincing myself to go for a run – which will make me sweat and ache – takes a lot of mental effort when my couch is so damn comfy.

But like physical activity, the more effort you put into forcing your brain to see things differently, the more it adapts and adjusts as well. There can be a new normal, and you can even be happy with that new normal. And once again the brain is smart – when you exercise hard and create that microdamage to your system, your body immediately releases endorphins to help you forget the ache, making you feel good.

It’s why exercise is now being prescribed to fight depression. You exercise, and then your body produces natural antidepressants/painkillers as a reward to distract you while it repairs the damage.

So I hate to shatter the myth created by the fitness industry that getting fit can be effortless, but the truth is: no pain, no gain. Sure, that slogan won’t sell DVDs or workout gear to people who are thinking about starting a fitness program, and I understand that. But I’m not selling anything, and feel like it’s time to be honest with people. It’s one reason I love shows like The Biggest Loser – the contestants lose a lot of weight, but they also don’t pretend that it’s ever easy.

I’ve weighed 250 lbs at my highest weight. I currently weigh 181 lbs. I work full time, parent two young children, and have a thousand other responsibilities. But I carve 35 minutes into my schedule to work out. Until this year, I never could have run the length of a city block without being winded. I’m now running for 25 minutes straight. I used to polish off a large Big Mac value meal and still have room for dessert. I now eat half of a Chipotle burrito bowl for dinner – loaded with lots of lean protein and veggies – and save the other half for another meal.

I have endured a lot of pain getting to where I am now, and I know there is more to come. It’s still a struggle to convince myself to exercise and eat right. But I also love how great I feel after a run, I love that I can play with my kids without being winded, and I’m thrilled at the changes I see when I look in the mirror.

It’s not all pain and sacrifice – I still eat comfort foods (just not every meal), and I still have days where I enjoy lounging on the couch. It’s all in moderation now, both the indulgence and the sacrifice, and I find that some sacrifices actually become indulgences as my way of thinking changes. I know the little bit of discomfort I’m going through now will help me avoid a lot more pain down the road, and hopefully will add years to my life.

I’m the average overweight American, and I’ve failed at all of the “easy” ways. But the hard way is working, and if it works for me, it can work for you, too. Surround yourself with supporters who know this will be difficult, who won’t try to tempt you with suggestions of an easier way. And get ready to face your greatest obstacle blocking your success: yourself.

I know my opinion is unpopular, and I guess that’s why I’m stating it here instead of trying to sell it. But join me in accepting “no pain, no gain” and I know you’ll improve your health and fitness.

Don’t fall for the hype. There is no easy way. You have to work hard to make your body work for you.

Full disclosure: Results ARE typical when you follow a plan of regular, moderately strenuous exercise and healthy eating.

However, just because I’m a nurse, don’t consider the above to be medical advice. Always check with your doctor when beginning any fitness program.