Cindy Blackstock, 41, Plymouth, Sivo Insights Partner, Ironman triathlete

Cindy Blackstock thought nothing of it when she went in for a routine mammogram last year. She had just turned 40 and was in the best shape of her life. A serious triathlete, she also had just qualified for the Ironman World Championship in Hawaii. But she was diagnosed with stage 2 breast cancer, propelling her on an intense journey that included plenty of soul-searching, surgery, chemotherapy and training. Less than a year later, Blackstock is heading for Kona on Saturday to compete with the world's elite triathletes.

A 6.2-MILE DARE "I was not an athlete at all in young adulthood. I met my husband [who's] been an athlete. He encouraged me, and I started running and could barely keep up. Next thing you know, I was whooping him. I did my first 10K on a dare in 1997, fell in love with running and then did a marathon. I qualified for Boston but I kept getting injured because I ran every single day. My husband started getting into triathlons while we had babies, and then I took them up, too — and stopped getting injured. It's a lifetime sport: swimming, biking, running."

AN UNEXPECTED TURN "In 2010 I trained for [Ironman] Madison, and the next day I said, 'I need to do that again.' In 2012 I did, and I qualified for Kona [where the world championship is held]. I was in the best shape of my life and my husband and I had just celebrated our 15th wedding anniversary. Life couldn't get any better. Two months later, I had stage 2 breast cancer. I made some quick decisions: I had a double mastectomy immediately. I was mostly thinking about surviving, but in the back of my mind, I was thinking, 'Omigod, am I going to get to Kona?' In January I started chemo. I did four rounds, and then had my second reconstructive surgery in April."

ROAD TO RECOVERY "I couldn't swim or bike while I was doing chemo because I was 'cold capping' [freezing hair follicles to prevent hair loss], but I could run. On the days I could run outside I had a smile plastered on my face. It made such a difference for me to be outside. I wasn't running at the pace I wanted, but running makes you feel human again — especially when I ran with my husband, exercise almost made me feel normal. Out on the trail, no one knows what I'm going through. I still wanted to get to Kona, even though mostly I wanted to survive for my family and friends and business partners. That goal really made a difference. My husband and my business partner [at Sivo Insights, a consumer insights firm] are amazingly supportive. And since we own our own business, I could work from my bed if I wasn't feeling great. We decided to donate 3 percent of our profits to breast cancer research."

NEW TRAINING PLAN "I started training again in May. I thought, 'You know what? I can do it!' I really believe I bounced back from surgery and chemo as quickly as I did because of the shape I was in. My body is not the exact same body; there was definitely some adjustment in terms of exercising. The muscles in my chest are just different; I feel different when I swim and bike."

EVEN IRONWOMEN "As an athlete, I think we tend to think we're invincible. When I got my diagnosis, I remember thinking, 'Wow, I just did an Ironman. I feel OK; I feel healthy.' I never felt [a lump], nor did my doctor. But when the mammogram reminder popped up on my calendar I thought, I'll just schedule it. I did self-exams and I had no family history, so it never entered my mind that it could be a possibility. But if I hadn't gotten the mammogram, I think I might not be alive … or my outcome may not have been as good. It saved one life. Isn't that worth it? I'd guess my kids would say yes."

ALREADY REWARDED "I feel great now. Sometimes I think, 'Did that really happen to me?' I feel like I'm ready to go; I'm back to where I was. I feel blessed to be able to get to the starting line. When I got the diagnosis last Nov. 28 I didn't feel like this was within the realm of possibility. So just going is — to me — the medal."