Tired of watching a dialysis machine keep his sister alive, Jeremy Bell decided to lose 100 pounds so he could save her.

Crystal Bell’s kidneys were destroyed by a congenital condition and her body rejected a kidney donated by her cousin 10 years ago, Bay News 9 reports. The Georgia woman badly needs a transplant, so her brother decided to get himself into tip-top shape and donate his own kidney.

"Would you push them out of the way if a car was coming?" Jeremy Bell asked Bay News 9, referring to saving a family member. "Would you protect them if someone was breaking into your house? I have a spare kidney. How could I not give it to her?"

As a general parameter, kidney donors should be in good health. Donors who are overweight or obese are more likely to experience long-term kidney damage themselves after the operation, according to the National Kidney Foundation.

Blood relatives typically make the best donor candidates, something Elissa Stein kept in the back of her mind as her own brother's condition took a turn for the worse. Stein’s brother had struggled with a host of debilitating medical conditions throughout his life, and when his kidneys gave out, she decided to step in.

“I've always known, on some level, that should he need one, one of mine is his,” Stein wrote in a blog for The Huffington Post. “I am grateful for all that my life is,” she wrote, "and I'm even more grateful that I can give something back.”

As Bell gears up to take on the same heroic role, he’s also working to raise $10,000 for his sister’s procedure, a feat he’s confident he will achieve.

"I just decided I needed to do it and started," he told Bay News 9. "You know, she's my sister."

Feeling inspired? Learn how you can contribute to Crystal Bell's fight for life here.

Click through the slideshow below to read more inspiring stories of donors who gave the ultimate gift:

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  • Best Man Donates To Bride

    Leanne Stefanovic, 31, found her soulmate with ease, but it was the best man who became her perfect match. <a href="http://www.huffingtonpost.com/2012/01/23/organ-donation-best-man-d_n_1224258.html" target="_hplink">He stepped up to donate his kidney to the bride</a> who had been chained to dialysis for four years.

  • Justin Bieber Tweets To Donors

    When Hélène Campbell, 20, hoped to spread the word about her struggle to get a lung transplant, <a href="http://blog.music.aol.com/2012/01/24/justin-bieber-twitter-organ-donor" target="_hplink">she turned to one of the most popular tweeters out there, @JustinBieber to spread her message. </a>"@alungstory i got the word....you have amazing strength," Bieber tweeted to his 17-million plus fans. "i got u. #BeAnOrganDonor"

  • A Craigslist Donor

    <a href="http://www.huffingtonpost.com/2010/09/27/sisters-use-craigslist-to_n_740577.html" target="_hplink">After three sisters found out they weren't matches to donate a kidney to their father</a>, they brought their plea to Craigslist. There, they found a donor and the inspiration to start T<a href="http://www.floodsisters.org/" target="_hplink">he Flood Sisters Kidney Foundation of America</a> to help pair donors with those in need.

  • Shooting Victims Save 12 Lives

    After Mary Ann Holder killed her niece and son, Hannaleigh Michelle Suttles, 8, and Zachary Lee Smith, 14, some hope emerged from the senseless tragedy. <a href="http://www.huffingtonpost.com/2011/11/25/hannaleigh-michelle-suttles-zachary-lee-smith_n_1113010.html" target="_hplink">Zachary and Hannaleigh Michelle's organs were donated, which helped save 12 people's lives. </a>

  • Daughter Saves Mom's Life

    When former HuffPost Impact editor Erica Liepmann found out that she was a match to donate a kidney to her adopted mom, <a href="http://www.huffingtonpost.com/erica-liepmann/mother-daughter-donation_b_844687.html" target="_hplink">the news felt that much more miraculous when Liepmann learned just how rare it is for biological strangers to be compatible.</a> "The fact that my mother didn't actually give birth to me, yet I still had the perfect organ to save her life, solidified my belief that this was fate -- perhaps even part of a divine plan -- for me to be the one to donate," Liepmann said.

  • Christa Taylor Green Lives On

    When the youngest victim of the Tuscon, Ariz., shootings died last year, the parents of Christina Taylor Green, 9, were determined to perpetuate her legacy by donating her organs, <a href="http://www.huffingtonpost.com/2011/01/16/christina-taylor-greens-o_n_809696.html" target="_hplink">a gift which helped at least one young girl in Boston. </a>

  • After Heart Transplant, Dancer Raises Awareness

    When Ava Kaufman, a dancer who committed decades to her craft, saw her body swell to a shocking weight, she knew something was terribly wrong.<a href="http://www.huffingtonpost.com/2011/02/22/ava-kaufmans-story-after-_n_826630.html" target="_hplink"> Kaufman was diagnosed with a rare autoimmune disorder and received a life-saving heart transplant just in time.</a> She now raises awareness for organ donations and supports patients awaiting surgery.

  • Woman Gives Kidney To Brother

    After her brother struggled for 45 years with a number of health issues -- starting with losing a kidney to a tumor at 9 months old -- Elissa Stein learned that she was a match to save her brother's life. <a href="http://www.huffingtonpost.com/elissa-stein/a-different-kind-of-givin_b_801290.html" target="_hplink">She didn't hesitate stepping up to help. </a>

  • One Child Saves Another

    After Hernan Perez died in a sledding accident when he was 6, his organs helped save a number of people, including Megan Corfee, now 9. <a href="http://www.huffingtonpost.com/2011/12/20/one-childs-heart-saves-an_n_1160757.html" target="_hplink">The families live just 30 miles from each other and work together to inspire others to become organ donors. </a>

  • Stranger Donates Kidney

    Charles Hoffman was getting desperate, so turned to MatchingDonors.com, a site that matches living donors to recipient in need and hoped for a miracle. <a href="http://www.huffingtonpost.com/2010/02/19/stranger-saves-mans-life_n_469729.html" target="_hplink">When Hoffman was saved by a complete stranger, he became the site's 114th success story.</a>

  • 2-Year-Old Saves Lives

    After 2-year-old Jariah Henderson was accidentally shot while playing at a relative's house in Gary, Ind., <a href="http://www.huffingtonpost.com/2012/01/17/jariah-henderson-organ-do_n_1210259.html" target="_hplink">his family donated his organs, helping to save up to seven lives. </a>