I don’t know about the laws in Canada; but in the US unless you have a “living will” instructing the doctors otherwise, the docs will do everything they can to keep you going. So, you could make a living will to instruct them to “do everything possible” but that is what they would normally do. You give a copy of the living will to whoever is probably going to be at the hospital when you have a medical issue. The living will is supposed to be in a sealed envelope, so whoever has it can’t see what you’ve requested & try to override your decision. In your case, I would think that 1 copy would go to your Mother. I don’t know who else you trust that you would want to give a copy to so you need to decide who that is. If you don’t want to pay a lawyer to do you a living will, you can go online & get a prototype that explains how to legally fill it out. Some libraries keep such forms on file & you can request one from them & make a copy for your purpose. The library might charge a nominal fee to make you a photocopy but it’s cheaper than a lawyer.
You need to check the requirements in Canada as to how they deal with living wills. Personally, I’d have a serious discussion with whoever you would give a copy telling them specifically what my thoughts are so they are prepared to follow my desires to the letter.