Never let anyone tell you it is too late either to start writing or to move genres. For inspiration, consider Andrea Camilleri, who was nearly 70 when he created Inspector Montalbano.
And on being true to yourself and your own vision for your writing, when her first book, Madam, Will You Talk? was taken on by Hodder, Mary Stewart was sent back an edited version. “She scribbled it out and said ‘My writing is better than your edits – please don’t edit my books if you want to publish them.” A recollection by Mary Stewart's niece, Jennifer Ogden.