No matter your age, wealth, or health, you should have a will. Without the right documentation, the courts decide what happens to your assets—and more importantly, the pets, children, and adults in your care. Children can end up in foster care if the court doesn't deem anyone acceptable or no one volunteers, and pets can end up in shelters. Unlike spouses, long-term partners generally don't have automatic legal rights to anything not also in their names.
Assets don't need to be financially valuable—sentimentality matters. This is part of why it's crucial to create a will, no matter how old you are.