I only eat low carb raw vegan food, which taste like cr@p.
Don't do this, as a vegan, this is the sort of nonsense that makes vegans look like morons. Carbs especially are the most readily used energy source for powering bodily metabolism. Also raw vegan food is even more idiotic, there's no basis that this increases nutritional yield (it's actually worse, as digesting raw food isn't trivial, and leads to less caloric and nutritional uptake).
The only thing you really want to watch out (seeing as you speak English, I assume you live in the US or UK) is to avoid high lipid content, and make sure you get the vitamins and minerals you need (can be confirmed with blood tests). Heart disease related risks in these two nations is sky high. Avoiding saturated fats and cholesterol have shown to at least halt any atherosclerotic progression. Also keep sodium intake as low as you can. Even the sliced bread I eat has a ton of sodium, even though I can barely taste any salt.
To make things worse, I'm an agnostic atheist, so I'm unable to assure my self that I'll be going to a better place. The way I see it, when you die, you "feel" exactly the same as you felt in the 1800's...
Well if you see it like that, then the inability to assure yourself of something no one can prove is simply a logic lapse you need to get to grips with.
sometimes I can't even fall asleep because I'm scared that I won't wake up in the morning (my doctor says that I have death anxiety and he proscribed me some Xanax, which I decided not to take after I read the possible side effects...)
Well, you've done some weighing of risks, though by the sound of things, xanax would be prudent seeing as how your anxiety sounds crippling.
How do you deal with this sad fact of life? How does it feel to be over 70, knowing you can go any day?
Seems somewhat natural, but this whole idea that you're going to croke over at any second is a bit ridiculous. Firstly, if it's instantaneous as you imagine, then there's no need to fear it, as you can't even prepare for it for something so sudden that will be over at any time.
But the thing you want to do to get off of this irrational thinking (if you're not suffering from some metal disease already), is make sure you visit doctors to see if you have any undiagnosed issues pertaining to age-related health risks. Like getting that aforementioned heart disease possiblity checked out (cholesterol levels should be lower than even the accepted averages, since those standards are not in line with literature of healthy levels). Check out if you have any early on set metal health issues like dementia or something. And keep getting screened for cancers yearly and such. Make sure you get daily exercise as well (quite important).
There's not much really left aside from the basics like drop drinking and smoking (and psychoactive recreational drugs if you partake).
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There's lots of defeatists out there that tell you to YOLO your life away doing w/e you want. But this seems like quite an ignorant stance. People seem to assume that by living however you feel like, and not waking up one day, is how most people die. When most deaths are prolonged, and agonizing ordeals. If one such condition of that sort catches you, the last thing you'll be thinking about is "where am I going to be where I die", and instead looking at how you can get it over with ASAP.
America for the most part not being an assisted suicide-friendly nation, you don't even get a quick end if you get caught with some debilitating disease as a result of a stroke, or some accident. So folks that talk about YOLOing, remind me of myself when I used to smoke at a teen. But when you dig into actual cases and see how sufferers of smoking live out their last days - you're going to wish you could slap whoever told you to live with such nonchalance.
(late 20's now, so take it as you will). I also worry how I might go, but there's no reason to live in some delitating fear of death - living in a first world nation especially (unless you're unlucky and fall off a flight of stairs and have to live in bed for the rest of your life or something). Try visiting multiple doctors if you feel the advice of one isn't to your fancy. But be careful about thinking you're smarter than all of them. Look into some anti-anxiety meds, it seems you may actually need them.