Getting old has advantages as well as disadvantages. it may mean that you are freed from obligations – work, bringing up children, looking after older relatives – that left you little time or energy for writing. If so, that new freedom could stimulate your creativity.
Whether you write fiction or non-fiction, your writing will be informed by your own life experiences – work, leisure, travel, friendships, relationships, love, loss…you name it. The older you gte the more life experiences you have to draw om.