There are also realities that exist when you do not exist. That reality was in the past, but it will also come to be again in the future. The one where you are unborn or deceased.
Both realities are equally valid. They just occur at different times.
Time is a dimension of the universe. Beyond height, width and depth it's the most obvious 4th dimension. (Physicists by the way talk about 10 dimensions in our observable universe. I can't get my head around that, but apparently it makes sense mathematically).
|A 4 dimensional cube|
Everything is relative. For example, distance is relative to the person observing it. I just moved 2cm to my right in my train seat. To the person standing on the train platform I just moved 10 metres in the same time.
Just as distance is relative to the person observing it, so is time. You are alive because you are the one observing yourself. You cannot observe yourself dead. But the reality of your non-being already exists, it's just that your position in time relative to it does not allow you to observe it.
If that's the case - I am already dead. I am alive and dead at the same time, just in different realities. Fortunately I experience the reality where I am alive, not dead - and I appreciate that.
This is a strange realisation. But strangely liberating.
Once you see life in pure relative terms with no absolutes, it starts to make more sense. You really appreciate the moment. You wake up each day with a zest to live and enjoy the moment. In the history of the universe, it is almost nothing. But we know it's not nothing, it's everything.
Live life knowing you're already dead. Try it.