When people are ill they often appoint someone they trust with their 'power of attorney'. This means that the nominated person can act on their behalf in case they become too ill to make their own decisions. Think carefully about who you appoint so that you feel confident that they will respect your wishes.
You will need to let the person know what you want so that they can make sure it happens. You will need to give them your letter of wishes, your recorded message or talk to them about what you do and don't want in person. You may also want to consider giving them information and guidance on dealing with your digital property, such as your email and social media accounts, the pin code to your mobile phone and relaying any passwords you think they may need in order to manage your affairs (such as online banking or shopping accounts). The person you entrust may also need to know about some of the practical things like your bank account details, information on utility bills, details of your rent or mortgage.