My secular answer is to live in a jurisdiction which allows assisted suicide, and to have a clear plan registered with my doctors, lawyers, and family.

My fear is that I will lose the decision-making agency quickly and unexpectedly and have my clear wishes disregarded for some stupid technical reason which would require someone to take professional or legal risk to fulfill them.

I've built a room in my house which is designed to be easily disconnected from the building HVAC such that I can safely discharge, and then automatically vent to outdoors, bottles of compressed gaseous nitrogen or helium.

For safety, the prep for discharge requires a few minutes of work, with hands and brain that are at least marginally nimble. I worry very much about the risk of waiting too long, or having a debilitating issue crop up unexpectedly (I am presently of sound mind and body, and not old).