Don't let the title mislead you.
I'm not saying that I live the life of a murderer, murder suspect, murder investigator, or murder victim. At least, I sincerely hope not! Let's set aside genre for the moment and just talk about characters and settings.
I grew up reading V.C. Andrews novels. Yes, I did! And one thing I noticed is that her characters (at least in her earlier series, such as the Casteel, the Cutler, and the Logan family series) went from one extreme to the other--dirt poor to filthy rich. There didn't seem to be any middle class in her characters. Never having been either extreme, I found it hard to relate to those characters (though the stories were a guilty indulgence, much like watching reality TV is these days!)
I suppose I could write about a wildly rich family and all their trials and tribulations, but I think I'm too practical minded. The very thought of hosting a multi-million dollar wedding for a child of mine makes me physically ill. So does the idea of paying full price for an item at Dress Barn when I have a coupon that will take 10% off. You get the picture.
Poor characters are ones with which I can more readily identify. Not that I've had to worry about starving to death on the streets (thank you, Lord) but I know the hollow feeling that comes with deciding which bill to pay and how to squeeze grocery money out of a squeezed-dry budget. I know what it feels like to skip a simple $1 cup of coffee from McDonald's simply because you need that dollar to pay for bus fare to your next job.
Living the life you write has to do with how the writer--and the characters he or she creates--deal with everyday life. Whether a character is rich or poor or in between doesn't change whether that character is whiny and self-absorbed or feisty and hard-working. It doesn't change how a character views the world around him or her. Either they are eternally optimistic and see beauty in the poorest surroundings or they're clinically depressed pessimists who will always find a flaw, even in Heaven. Either way, the story will be unique to that character.
It's good to have a mixture of characters and settings, but ultimately, it's the author's perceptions that color the characters' world.