Your friendships are doing more to boost your health than you may realize.

Getty Images Between your gal pals, the ladies in your Zumba class, online buddies and work chums, you probably have even more friends than you realize. And that's significant: "Having lots of ways to connect is important, especially during midlife, when women are bogged down with balancing work and family, and can use all the support they can get," says Irene S. Levine, PhD, a psychologist in New York City and author of Best Friends Forever. Three groups of friends share stories about how they got each other through times of crisis, bolstering their bonds along the way.

My friends helped me survive cancer

When a doctor told Katya Lezin in 2011 that she had ovarian cancer, she assumed the worst and considered the diagnosis a "death sentence." After breaking the news to her husband and her three teenage children, the Charlotte, N.C., college adviser phoned her closest friends: Lorrina Eastman, a 46-year-old psychologist and mom of three, and writer Lisa Zerkle, 46, also a mother of three.

Katya: "Lorrina assured me that we'd be in this together and spelled out ways she'd help, like arranging for meal donations and planning a carpool to get my kids around. It took such a load off my mind. That week, Lorrina ordered bracelets from the American Cancer Society that said 'Courage'—they symbolize ovarian cancer awareness—and gave them to friends and family, which helped my kids feel bonded with everyone in my support network."

Lorrina: "The news left me numb. Katya's like a second mother to my children."

Lisa: "The chemo sessions were going to run up to 10 hours long. I made a schedule so friends could sign up for two-hour slots to wait with Katya. I also delicately turned away well-intentioned acquaintances when she felt like being alone."

Katya: "I'd get incredibly nauseous or totally loopy from the drugs, but Lisa's chemo-buddies idea was a highlight of my cancer journey. When friends overlapped between shifts, it turned into a big gabfest. At the end of the regime, one friend even said, 'Don't take this the wrong way, but I'm sad that your chemo is over.'"

Lorrina: "Sometimes Katya was so sick, and helping her family was the best thing we could do for her. I went to her daughter's winter concert at school and picked up a birthday cake for her youngest. Toward the end of her chemo treatments, she was exhausted but decided to run the annual Race for the Cure anyway. I ran with her—for support, and to make sure she didn't collapse. It turned out to be an empowering experience."

Katya: "As we crossed the finish line, I began sobbing. It was cathartic."

Lisa: "Classic Katya—she turned her experiences into a book, But I Just Grew Out My Bangs! A Cancer Tale.

Katya: "I'm nearing my two-year cancer-free mark, and I'm optimistic. In March, Lorrina and other friends organized a big birthday party for my 48th. I was 'kidnapped' for the day and taken from one fun activity to another, like a scavenger hunt. They've also planned three different weekends away for my husband and me. It's like I tell my kids, 'Life is not about how you act at Disneyland, it's how you act when things aren't going your way.' My friends have always been wonderful in good times, but I've been blown away by how they came through in the bad."

We lost 148 pounds together

Cincinnati high school teacher and mom of two Cheryl Buccino, 46, vowed to lose weight after hitting 209 pounds a couple of years ago. She found inspiration right across the hall: fellow teacher Natombi Simpson, 43, a mother of one who'd once weighed 248 pounds but seemed to be getting smaller and smaller by the day.

Cheryl: "It took months to ask how she was doing it. "

Natombi: "I knew how it felt to be bigger than you wanted to be. I knew I could help her."

Cheryl: "Natombi was hyped up about Weight Watchers, so I joined, too. She'd text me things like 'Tell me what you ate for lunch.' At the end-of-year school cookout, we brought our own salad and angel food cake."

Natombi: "It was never a competition! Having her to share successes and setbacks with made losing much easier. I got Cheryl—who swore she couldn't clap in time to music—to try Zumba. And she helped with my body image: Even after I'd lost a lot of weight, I stuck to baggy clothes. She got me to try more fitted ones."

Cheryl: "One day Natombi twirled around in the hall to show me her jeans—a size 8, down from a 22. We were jumping up and down."

Natombi: "I've lost 93 pounds! Inspiring Cheryl keeps me motivated still."

Cheryl: "I've lost 55 pounds and feel years younger. If I screw up and overeat, I start fresh the next day, no guilt—something Natombi taught me."

My best friend saved my life

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Kelley Cone, 47, and at-home mom Denise Hus, 48, met while cheering on their sons at high school basketball games in Midland, Mich. In March 2011, before a joint vacation, Denise got a painful cough that wouldn't go away.

Denise: "Kelley kept bugging me to get it checked before we left for Florida. At school, she spotted me and yelled, 'I'm going to drive you to Urgent Care myself if you don't take yourself.'"

Kelley: "I figured that with antibiotics and rest, she'd be good to go."

Denise: "At Urgent Care, a chest X-ray revealed a suspicious shadow. The doctor told me to go for a CT scan. The results showed an aortic dissection—a tear that could lead to a fatal rupture. I sat with my husband, Mike, in shock while ER nurses and doctors rushed into the room. I kept repeating, 'Is this really happening? I feel fine.' They scheduled me for open heart surgery the next day."

Kelley: "When I got the call from Mike, I didn't believe it. It was freaking scary. But then I was relieved that I'd nagged her that morning."

Denise: "I was most worried about my three boys. It helped knowing that Kelley was preparing their meals and distracting them with activities. She kept my spirits up, joking that this was the last trip I was going to get out of! The surgery went fine. My doctor told me my cough was actually unrelated to the aortic dissection—it was just a blessing that I had gotten it checked out. My heart would never have withstood a flight. Kelley saved my life—something I shared when I spoke at an American Heart Association 'Go Red' event."

Kelley: "I don't want credit; any friend would've done the same. I still turn it back on her, like during a toast when our families go on spring break. I'll say, 'What would we do without you here?'"