I start with accepting that death will happen for everyone, and relating to that, instead of pretending it won’t.
I also have long related to what “I” am as something not really the same as this physical body, thoughts and life. The one constant is always my conscious perspective, which is always the same. I’ve met this perspective again in ancient spiritual/mystic traditions, and it feels accurate to me.
That perspective also resonates with my experiences and way of being in some times of great illness or danger.
I’ve also read with interest many perspectives from people who have researched near-death experiences and past-life hypnotic regression and other such experiences, including skeptics and people who are rational and pretty clearly not attention-seeking charlatans, and it appears to me pretty clear from this (consistent with the intuition and traditional teachings I mentioned before) that some part of our consciousness exists outside a single life.
I’ve also experienced contact with ancestral spirits, and know people who practice ancestral healing work, which I’ve found to be extremely valuable, and which incidentally also fits in with all of this.
But even if I didn’t have any of the notions of consciousness being more than one physical life, I also had a realization when I was about 18 that it would at least eventually become “all right” to end this life. I’ve already had a good life, and thought I’d like to enjoy much more of it, I know it will end, and I wouldn’t relate to it as a tragedy even if there’s nothing more, and even if it had ended much sooner.
And particularly when relating to the death of loved ones and other others, while I miss them and could wish for more, I find comfort in realizing that all people die, and thinking of the great and positive things about those lives. There’s little point in wishing they were immortal, or that the past had happened differently, and less point in raging that those wishes aren’t true.