• Become insensitive to exposure to cold water by, for example, frequently taking cold showers or ice baths. This apparently helps with weight-loss as well. I've done this with immense success, and even some real-world application (hiking to a waterfall with my parents, and being able to swim without getting cold). After you've practised this, you will literally feel like some weird heat is being generated from someplace inside you when are exposed to cold water, and not feel cold at all. See here.

My "possible unacknowledged major risk" detector triggered on this paragraph. In particular, "you will literally feel like some weird heat is being generated" pattern matches against how I've seen hypothermia described. While I don't know enough about it to say for sure if this is necessarily bad, I will say that the required due diligence for this is substantial, and the potential upside doesn't seem very compelling.

The rest of the list looks like mostly good ideas, though.