If you are...
  1. Under 25
    Good for you! Go put your dent in the universe.
  2. Under 27
    At your age Ernest Hemingway had not published anything of consequence yet but he was trying.
  3. Under 30
    At your age Harrison Ford was supporting his family doing carpentry work having failed as an actor. He finally landed his first significant role at 29 in George Lucas' American Graffiti.
  4. Under 35
    At your age Andrea Boccelli decided to pursue a career in opera.
  5. Under 40
    At your age Stan Lee was still a few years away from embarking on a career drawing comics.
  6. Under 41
    Maya Angelou was still months away from publishing her first autobiography, 'I Know Why The Caged Bird Sings'
    Suggested by @emily_halpern
  7. Under 45
    At your age Julia Child, after studying culinary arts for five years, published her first cookbook.
  8. Under 50
    At your age award winning fiction writer Donald Ray Pollock started taking English and writing classes at Ohio State while still working at a paper mill. His marriage was strong, his kids were grown, and he thought he might like to try writing.
  9. Under 60
    At your age, Laura Ingalls Wilder hadn't yet succeeded in publishing Little House in the Big Woods, the first in her classic series.
  10. Under 70
    At your age Anna "Grandma" Moses was still doing embroidery as a hobby. At 76, arthritis made it difficult to carry on so she tried painting as an alternative. For the next 25 years she completed over 1,000 paintings, exhibited all over the world, and achieved national acclaim as a folk artist. Her work appears in museum collections and pieces have sold for over a million dollars. (Hat tip to @ChrisK)
  11. Under 80
    At your age, Iris Apfel was about to embark on a second career as the fashion world's mega-darling "Rare Bird of Fashion". Over the next ten years, she would be featured in every major fashion and style magazine throughout the world, as well as two major motion pictures, including the eponymous IRIS.
    Suggested by @lilydiamond
  12. Thanks to awesome suggestions we're up to 90. Can we find one?!