Below is a link to a short video in which children's picture book writer Pat Zietlow-Miller talks about how she came to realize her writing dream.
She was 39 when she started going for it seriously, and she had 126 rejections. What's more, even though she's now had several books published, she still gets rejections.
The secret of her persistence: she loved writing so much that she'd do it whether or not it ever got published.
(If you want to write, find tips and support in my book, Your Writing Coach, published by Nicholas Brealey and available from your favorite bookseller.)