Definition of "never give up"

My Aunt Polly turned 90 last month. She lives by herself. She still drives (responsibly), and she tells me that I drive "like a little old lady." She was born in Greece, came to the United States in an arranged marriage, adapted by learning to speak English and by applying her experience in sewing to become a highly celebrated and well-loved designer and seamstress.

The story behind the story? To keep it short: She couldn't have children of her own, so she unofficially adopted others' children, including me and my sister. She has countless "grandchildren" who love her, visit her and consider her their only or their bonus grandmother. She has always kept a smile on her face and a positive attitude. She's had surgery over 13 times (we stopped counting) and so many MRIs and CTs and other testing and procedures that it's amazing there's any blood or patience or emotional stability left in her body! She lives in constant pain but rarely admits it or talks about it. She nursed my father (her brother) in his troubled years, through his Hospice years and saw him through to his transition from this world. She visits others when they are sick, bakes cookies and cakes to share with neighbors and friends, makes baby blankets to donate to the local hospital (for newborns whose parents don't have such supplies) and volunteers in the kitchen at Meals On Wheels.

This is my aunt with all of her "daughters" and "granddaughters" at a family wedding recently.

Her ongoing optimism, which is bolstered by her religious faith and the kindness of others; her smile; her enthusiasm for supporting others and her expression of gratitude through having fun, these are the things which have carried her all the way to 90 and, who knows, probably to 100. Now, that is as good a definition as I can find of "never give up." What is your definition?