The January after I turned 39, I resolved to get as fit as possible by my 40th birthday. Anyone who has ever seen that number approaching can relate to the urge, I'm sure. I thought perhaps looking good might soften the blow of the big four-o. And sure enough, it did.

What I did wasn't rocket science. I started eating mostly protein, eliminated processed carbs, and began doing HIIT workouts up to six days a week. Eight months later, I had the results I was looking for; I dropped 20 pounds of fat and built some lovely muscles. In fact, on my 40th birthday, I weighed the same amount I did as a senior in high school. Being able to say that felt good.

So...end of story, right? Hardly. Like many before me, once I had opened the Pandora's box of fitness, I quickly found myself embarking on a new adventure I couldn't have dreamed of. It was spurred by an offhand question from a mere acquaintance, and it gave me a lesson in willpower unlike any I've ever experienced. Here's my story.

After my eight-month-long transformation, I was proud of myself. With a 5-year-old, a (rather stressful) full-time career, and at "middle age," I had dropped a few pant sizes and was sporting some shapely biceps. Friends who hadn't seen me in a while were amazed. "Wow, you're crazy fit now!" they'd say.

Yeah, I looked pretty good...in clothes...for a 40-year-old-mom. But for a fitness model? Umm, not so much.

Honestly, I was feeling pretty cocky. And then one day, a friend of a friend casually asked me a question. "Hey, I'm working on a fitness-photo portfolio. Would you consider modeling for me?"

And all the air went out of the cocky balloon.

Yeah, I looked pretty good...in clothes...for a 40-year-old-mom. But for a fitness model? Umm, not so much.

But I was flattered, and for some crazy reason—maybe because I was flattered—I said yes. And then the panic set in.

The shoot was scheduled for three weeks out. In a sweat, I contacted the co-owner of Armbrust Pro Gym, Brian Leben, whom I'd met once, and begged for his help.

Now, let's be clear, Armbrust isn't just any gym; it's one of the best gyms in the world for training bodybuilders. Up to this point, I'd only been there a couple of times to work legs in their legendary leg room. But now, well, shit was about to get real. I didn't even realize just how real.

Becoming A Bodybuilder

I met with Leben and explained my plight. He agreed to put me through three weeks of a bodybuilder-style cut, and to give me the nutritional guidelines to match. I'm not going to share the specifics, because I don't want you to be tempted to do the same thing, so let's just say that the approach was aggressive because the time frame was short.

We began with a full-body scan to determine my starting body composition. Not bad for an old chick: 15.3 percent body fat. I felt pretty good about it, but also realized that it's hard to affect change on a number that's (relatively) low. But I had already committed to doing the shoot, and I love a good human experiment. My new coach was still game, and we decided to train together every possible day until the photo shoot. And I promised to follow his instructions to the letter.

We began with a full-body scan to determine my starting body composition. Not bad for an old chick: 15.3 percent body fat.

My inner dialog during the first few days went something like this:

[Looks at the list of foods.]

There are only like five things on here. And they all have to be prepped and cooked. I'm going to starve.

Two gallons of water a day? That sounds doable. Oh...crap. That's more than 30 glasses of water a day. I'm going to drown.

[In weight room on first leg day.]

I'll be OK in here. I'm pretty damned fit. [Five minutes pass]. Oh sweet jeebus, I'm not ok, NOT ok.

Just don't puke. Nobody likes a puker. OMFG, did I just throw up little bit? No, I think that was just a piece of my left lung.

These weights are psychotically effing heavy. Lifting them until failure suuuckks. Oh for the love of all things good and evil, this has got to end soon. I wonder if one of these ripped giant guys will carry me to my car?

[Nearly every day of the experiment]

Good morning, fasted cardio—you evil bitch! Seriously, I have to pee again? And I'm starving, even though I'm eating freaking constantly.

I never thought I'd hate steak. Fuck you, steak. And you too, oatmeal. You're miserable. Sweet potatoes? Not so sweet anymore. Yeah, fuck you, too.

There Is No Escape From Photo Prep

One sore-bodied week into the training, I went on a two-night mini family vacation. It's hard as hell to eat at the level of clean I was eating even at home, and I knew it would be even harder to do it correctly on the road.

As I limped into the car with a cooler full of cold sweet potatoes, mushy, unsweetened oatmeal, and a 5-gallon jug of water, I thought sadly, "Who am I? I used to eat Cheetos and Red Vines on road trips."

But as I slammed the car hatch on that stupid cooler, I smiled. I didn't miss the out-of-shape junk-food-loving old me. I was digging the strong woman with mountains of willpower I'd discovered. I realized that the new me was a badass in an entirely different way. It felt like a better way, even if my internal dialog didn't always recognize it.

I'll just say that, even when you're a badass, cold oatmeal out of a plastic baggie is disgusting. There's no way around it.

I found a gym immediately upon arrival at the hotel and got right to it. I don't imagine that I looked super cool during my workout there; I was still more or less a weight-room novice. But I stayed for two hours, trying out every machine and lifting heavy things until my whole body burned.

On the second night of the vacation, my family and I went to a five-star restaurant, and I allowed myself a few bites of chocolate cake and a glass of red wine, after my meal of salad with no dressing and salmon with no butter or oil. Even though it was a planned transgression (and a tiny one), I woke up the next morning with searing guilt that I had broken my "training." I vowed not to do it again. I headed home with even greater resolve to rock this experiment.

MAYBE I CAN DO THIS!

Back home and back in the weight room with Leben, I quickly realized that my road trip workouts weren't actually that hard after all. I was reminded of what the term "burnout" means and how achieving this state is definitely not pleasant. When I started to slow down or get lazy, Leben would firmly say "hard work" and set me straight. That phrase and I developed a love/hate relationship. Mostly hate.

One day at the beginning of the third week, i left the gym and had a moment of revelation. I felt amazing! It was like i could fly. My mind was clear and focused, and my body looked better than it ever had.

At one point, when I was at a low—there were a few of these, by the way—Leben said I was showing "improved form and muscularity." It felt like a sympathy compliment. But I took it, and I came back the next day to do it again.

It gave me a glimpse into why people do this. But how they do it continued to elude me. Seriously, over the course of the three weeks, I can't tell you how many times I wondered or said, "How in the hell do these bodybuilders do this?"

Experienced bodybuilders in shred mode come to the gym and work their bodies at a punishing level, and then they further challenge themselves with incredibly strict diets at home. They do it every day for months or years on end, just to add another pound or two of muscle or "bring up" a body part.

If we could harness this level of willpower and drive, we'd be able to achieve world peace, solve the energy crisis, and end global hunger. Through this process, I developed a tremendous respect for this lifestyle. Bodybuilding is hard! Not like a little hard—like, superhuman hard.

And yet, for a short time, I did it. And I survived. Even more than that, one day at the beginning of the third week, I left the gym and had a moment of revelation. I felt amazing! It was like I could fly. My mind was clear and focused, and my body looked better than it ever had.

That feeling lasted for two days. And then we cut my water.

In Front Of The Lens...Finally!

It's amazing how taking one little ingredient out of your life can change everything. Water is one of those ingredients.

But thirsty or not, since the shoot was in a few days, it was time to make me less "puffy." We tapered down to a gallon per day. Not so tough. Then a half gallon. The day before the shoot, no water at all. We also added in supplements to "dry me out" even more. And boy did I feel shitty, more or less like a lightheaded rag doll.

During this time, we had my body composition remeasured. I was petrified that there wouldn't be any change. That would have crushed me! But gloriously, there was change—big change! My body fat was down to 13.3 percent, far lower than it had ever been. My lean mass had increased significantly, and my body weight had decreased by 8 pounds. I skipped out of the gym (or my best dehydrated approximation of skipping). I was so happy.

Finally, the day of the shoot arrived! I was more than ready to complete the experiment. It had been about as long and tough as any three weeks of my life. That morning, I was allowed to have pancakes with syrup, two pieces of bacon, and a cup of orange juice for breakfast.

Best meal of my life. No question.

I'd gotten a spray tan and wax the day before, so my skin was ready for my close up. Plus, an hour prior to the shoot, I covered my entire body in Preparation H (I'd read online that it would help tighten the skin around my muscles), so I was glistening from head to toe.

So, smelling like an old person, and feeling slightly high off the OJ, I made my way to the shoot. And rather than feeling shy or vulnerable, I found it was so much fun! I was completely empowered by the fact that I had nothing to hide. I spent two hours with my photographer friend capturing shots of the best body I've ever had. I'll have those images when I'm 95 and wrinkly.

And still lifting. Because as it turns out, I'm hooked.

Pass me the sweet potatoes. It's leg day tomorrow.