At age 52, Amy Carr Curren realized it's never too late to take control of your health. Today, she's nearly 50 pounds lighter and feels healthier and younger than ever.

My struggle with weight started after I had my first baby in 1992. I had always been active and thin, running up to 9 miles a day, but my focus shifted when I had my son—I didn't feel like I had time for exercise. Then I had my daughter Molly 4 years later, and the exercise break continued.

For the next 10 years, my weight fluctuated, until I got divorced in 2006, when I lost 20 pounds. Some people eat in response to stress, but I did the opposite.

After I met and married my second husband Brion in 2008, the weight crept on again. I think I wanted to show off my culinary skills. I made very rich, fatty meals—lots of creamy sauces, fried chicken, corn with butter, bacon, and gravy. Both he and I gained a significant amount of weight.

MORE:7 Weird Reasons You're Gaining Weight

At this point in my life, my eating habits got out of control. I ate everything I could get my hands on. I cooked and baked, munching on chips and cookies all the time. My husband and I fed off of each other—we both loved food and didn't care about the nutritional value of the foods we were eating or the health effects. It was nothing for us to split an entire package of chocolate cookies in one sitting.

Needless to say, we both paid the price. I didn't weigh myself often, but I could feel myself getting heavier, and my jean size grew. I had headaches, reflux, and achy joints almost constantly. Then one day I was trying to put on my size 16 jeans and they were too tight. I am a small person, a little over 5 feet, and I weighed 185 pounds. The thought of having to go out and buy a size 18 made me want to cry. That was my wakeup call. I said to myself, What the heck are you doing? I walked into Anytime Fitness soon after, on February 11, 2013.

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I met with a trainer, Shane Barker, 3 days after I joined the gym. At first, I had a chip on my shoulder. I thought he was cocky and full of @$?!. Who was this ex-Marine to tell me, a 52-year-old woman, how to get into shape? I debated whether or not I should hire him as my trainer. My husband was very supportive and encouraged me to move forward. I wanted to make him and my kids (and myself!) proud, so I did. After my first few workouts with Shane, I hurt like I've never hurt before. But it was a good hurt, and I noticed I looked more toned soon after I started. Within a month, I lost almost 10 pounds. I felt a thousand times better and had so much more energy. I thought, Maybe Shane knows what he's talking about after all.

MORE:6 Ways To Get Started When You Have 50+ Pounds To Lose

The exercise part was definitely key, but I knew I needed to change my diet, too. I started researching clean eating—a dietary plan that stresses eating whole, unprocessed foods. I ditched the creamy sauces, cookies, and processed chips and started eating egg whites, vegetables, fruits, and nuts. It was when I started eating clean that the weight really started coming off. (JoinPrevention's 21-Day Challenge to lose weight and feel amazing by summer!)

As I built my nutrition, muscles, and endurance, I built up my confidence, too. I started running 5Ks and participating in mud runs. I road two half-century rides, and I finished a duathlon last year. I felt—and still feel—like I can do anything!

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Currently, I work out at the gym at least 5 days a week, 3 of which I do a high-intensity interval training routine. I love the combination of lifting heavy weights for 20 to 30 minutes and then sweating with a good cardio workout, complete with battle ropes and rowing. I particularly enjoy strength training; I recently did a 400-pound leg press!  My husband and I regularly participate in local cycling races and rides as well.

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In terms of my weight, my size 16 jeans went out with my creamy sauces and fried foods. I am 40 pounds lighter (a size 6—yay!), and I feel so much better than I did before. I rarely get headaches, and my reflux stays under control as long as I stick to my clean meal plan. It's definitely true that you get out what you put in. Once I got the junk out of my system, I stopped feeling so junky.

MORE:Your Simple 3-Day Diet Detox

At work as a full-time nurse, I now know how to better answer patients' questions about diet and exercise. In fact, I decided to learn even more by studying to become a personal trainer. On Saturday mornings, I run a boot camp in the local park. We have a blast! And my trainer Shane is now also my boss. He hired me to work in the gym, specifically to work with stubborn middle-aged women like my former self who may not appreciate a young male giving them workout advice. I tell these women, "I've been there. I know what you're going through. You may be sore in the morning, but you will thank me down the road."

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In both roles, I teach the people I work with to eat a diet as close to nature as possible with NO processed foods, especially those labeled as "diet." And perhaps most important, I tell them to never feel you are too old to start taking control of your health. If someone would have told me 3 years ago I'd be a personal trainer, I would have said they were nuts. But here I am, almost 55 years old, out there kicking butt in the gym.

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The best thing is, I actually feel a lot younger than I did before.  I run circles around my coworkers, who often turn to me for advice on healthy eating and working out. I am also so much more open-minded as a person, ready to take on any new challenge that comes my way. I tell my daughter I plan to be the 96-year-old on the dance floor celebrating her 60th birthday. Cue the eye roll...