When I was younger, people often said to me that I've got to live my life before I will really have anything interesting to write about. I beg to differ. Young writers are often in the position to use their imaginations, because they don't quite have the weight of the world on their shoulders yet.
Years ago I used to teach creative writing workshops to children and teenagers, and was always pleased with what they came up with. The world was full of possibilities for them, and if our world didn't have what they were looking for, they'd invent another world.
I admit that I often feel like I lost my mojo for writing. There was a time when I could write half a dozen new poems a day, and a short story in a couple of days. There was so much to write about, because everything interested me. I could sit next to a stranger on a plane, listen to his life story, and be completely fascinated.
Things are different now that I'm older. I try to fall asleep or bury myself in a book as soon as I board a plane, because I want to ward off conversation. When possibilities come up for how I can spend my time, I reject most of them because they just don't interest me, and I figure they will just lead to more problems, so I prefer to keep a low profile and do the bare minimum. I used to look at something and see the magic in it. I could write a poem about anything from an interesting perspective. Now everything just appears to me as being mundane and predictable. I have a "been there, done that" attitude.
So, if you are a young writer and have people around you trying to discourage you from doing what you love, just remember this: You shed many skins as you grow. There is no guarantee that you will keep the skin that motivates you to write. Use it while you've got it. There are no rules that say you have to live your life before you can write. Not everything has to be a memoir or autobiography. You can create whatever you want. The possibilities are limitless.