For some, it hits them during the "mid-life" crisis. For others, it may be an event that accentuates our mortality, like a close friend passing away. But regardless of when it happens, it's something we all feel. The desire to know you made some impact on the world before you die.
It may sound morbid, and perhaps the desire isn't as strong in some as it is others, but we all have it to some degree. Early on we settle that we won't be the next Abraham Lincoln or Steve Jobs. Our names won't be written in text books and biographies won't be written about our lives, but maybe some group of society will remember us for what we accomplished. Our life will be synomous with something important.
But what if we die without accomplishing that thing that will get us remembered? Is it enough to leave a legacy for our children? Our family? I don't know the name of Abraham Lincoln's parents, but they were pretty necessary for him to be. Your family name might not make it into the history books, but your kids will forever remember the impact you made on their lives.