I hadn’t heard from my friend Chris in over three years when a post from him showed up in my Facebook feed last autumn: he needed a new kidney to live.

I could hardly believe it. When we worked together as restaurant servers 10 years ago outside of Pittsburgh, Chris played softball and volleyball. In his late 20s then, he was the picture of good health. Since that time, his health had gone downhill due to a potentially fatal condition called chronic kidney disease—which causes the kidneys to stop filtering blood as efficiently as they should. The only cure is a transplant.

RELATED: 12 Weight-Loss Secrets From Celebrity Chefs

I messaged Chris right back. He replied that he was trying to stay positive, but ti was a challenge trying to find a donor who shares his Type O blood, which is the least common type. I happen to have Type O blood as well. So without even thinking, I wrote, “I have two kidneys. Both work. You’re more than happy to have one.”

When he read my offer, Chris broke down and started crying, I found out later. His message to me in return said, “you have no idea the encouragement you just gave me.” Donating my kidney was not a hard decision for me. My thinking was, his life is as important as mine.

Becoming a donor

Soon after our conversation, I started the process of becoming a kidney donor. I got on the phone with Chris’s transplant coordinator, who took my medical history. That was followed by an entire day of testing at the University of Pittsburgh Medical Center and a visit with a psychologist. Everyone wanted to make sure I was physically and mentally prepared to give up one of my kidneys, which I was.

The final step two months later involved speaking with the two surgeons scheduled to perform the operation. “It’s great that you want to do this,” both told me, “but you’re too heavy.” At 5 feet 7 inches tall, I weighed 218 pounds—but I needed to weigh less than 200 pounds to be approved as a donor, they said. 

My first reaction was shock. I’m too fat to save someone’s life? I thought. The doctors explained that they made the call because being overweight put me at risk of having health problems down the road.

I was upset and felt terrible for Chris. But as hard is this was to hear, I had to admit that the doctors made a good point. The truth was, I had not taken good care of myself since my son, now 3, was born. I’d gained a lot of weight, but I didn’t have the motivation to start working out or change my eating habits. Yet now, I did have that motivation: Chris’s life depended on it.

Motivated to make changes

As a restaurant manager, I have access to plenty of healthy foods, but I was more prone to eating a plate of fried cheese sticks. So the first thing I did was give up all fried foods. Instead, I ate salads, grilled chicken, cottage cheese, and fresh fruit.

Next, I put an emphasis on getting active. My company happened to be holding a 5K a few weeks after I began my weight loss journey. How hard could it be? I thought as I signed up. Well, it was the worst thing ever. I was out of breath, my muscles ached, my knees hurt, and I was soaked in sweat. But I made it to the finish line. Afterward, I hung the medal in my car and vowed I would keep running until I could run 5K every day.

RELATED: Best Snacks for Weight Loss

As a working mom, my time is limited. But I made a point to get in a run, or at the very least a walk, every single day. I set my alarm clock for 30 minutes earlier than usual to do it in the morning, or I forced myself to be active late at night while my ex-husband watched our son. By the end of 2016, I was able to run 3 miles, no problem.

40 pounds later

My drive to lose weight started out as a temporary thing; I just wanted to get under that 200 pound cutoff and be able to donate my kidney to Chris. But every day, I woke up feeling better and better, and soon, my new eating and exercise habits were a regular part of my life. This spring, I joined two local running groups and even finished a half-marathon. Instead of dropping just 18 pounds, I’ve lost 40. I feel so much healthier and can’t imagine going back to how I used to be.

To get our best wellness advice delivered to you inbox, sign up for the Healthy Living newsletter

I didn’t want to worry Chris, so I only told him recently that his doctors gave me the okay to donate my kidney. The transplant surgery is likely to happen this fall (doctors are trying to hold out until Chris’ kidney functioning becomes truly critical). I’m not frightened by the surgery, which is generally considered pretty safe for donors. In fact, I’m less scared about that then I was running the half-marathon this spring!

The amazing thing about this story is that I went into it hoping to save a friend’s life—and in a way, he ended up saving mine.