This is where this blog began. Tolstoy's Bicycle (by Jeremy Baker, originally published in 1982, now seems to be out of print but plenty of copies available on Amazon) has the subtitle who did what when? and clearly proves that there is no limit to what people can achieve, no matter how young or old they are. Tolstoy first rode a bicycle (which was then a new contraption) when he was 67.
I've met dozens of inspiring people over the years, achieving things that might not be expected "at that age"; my own first 5 km race at the age of 44 is a contribution too; and there are thousands of stories all over the world to inspire us.