Have that conversation right now with your child or children.
It is far easier emotionally, while you are still hale and hearty, than it will be, when you see the end approaching.
Make your will, jot down your wishes regarding a funeral and make a list of where all important documents - birth, baptismal and wedding certificates for you and a spouse, whether living or dead, if you have or have had one, deeds to your house, details of all and every insurance policy, car registration, banking details, and where all these papers are.
Remember too to leave instructions and authorisation for someone or other to cancel your accounts on LinkedIn, Facebook and all the rest of the digital sites you use.
And while you are about it, decide whether you really want your children reading your old love letters and other private letters, diaries etc. If you don't either burn them yourself, or leave very clear instructions as to their disposal. Same applies to photos.
If you have a pet, or pets, leave clear instructions as to whom you want to assume responsibility for them, and what form it is to take, if you still have a pet when you dies.