The Digitalis's flowers show the life of a flower so well; from birth to death. I don't think these fowers are aware of their life like we humans are. Dying might therefore not be such a big psychological deal for one flower as it is to us. After dropping dead on the ground, it's stuff becomes part of the ground, that after a while becomes part of new plants, again!

Biological basis
The general idea of human lifetime, from a distance, is: the fusion of an egg with just one sperm, being born, grow up, have kids, grow old, and die. One can have no kids or die at any stage too.
So, simplyfied ever more, someone's life is the period in between fusion and death. At about 1/3 of a lifetime, the children are made, starting new beginnings of ends, and by doing so the presence of life continues. But there are more views on life.

Long lasting shapes
The universe we live in is full of energy. The motions of energy have a changing effect on all shapes. Digital information with life error correction and multiple backups at physical distant locations have a very high chance on surviving the declay caused by the motions of energy. But even that can in some rare cases become corrupted or even destroyed.

I change
A human body changes a whole lot during its lifetime. I am not like I was 12 years ago, and the differences between me now and the day I was born are incredible. It's amazing how the human body manage to maintain most of its shapes from day to day.

Growing down
I don't like getting older, and seeing my friends growing old. It's cool to grow up when you're young, but it's terrible to grow down towards death. I think the mental health can stay fit much longer than the physical body, but when the physical body of the brains is growing very old, it will effect the mental health also.

We primitive
It's too bad that we grow old and die. Our shapes simply decay by all the motions. That's just the way it is. Almost all the energy we have, we have to spend on simply staying alive as individuals and as a group/spiecies. To improve our lifetime possible to about the point of imortal, we'd have to redesign ourselves completely. We could then spend our energy on discovering the universe and the optimum shapes of life. But we aren't ready for that yet. We still fight each other, instead of working together really well. If I were an advanced alien, I'd probably not be interested in these primitive humans on this Earth called planet.

Recognizing Life
A lifetime is a matter of recognizion. We do or do not recognize some body to be alive. And sometimes we're not sure how to label something, like a virus; is a virus alive or just some biological piece of code?Countless cells in our body die every day, and about as many are created every day.

Imortal Matter
From a matter point of view, we already are imortal, or very long lasting at least. The stuff we're made of doesn't come from nowhere, and when we "die" our stuff doesn't go nowhere. It came from within this universe, it's in this universe, and it will stay here. It's always now, and what we're made of is always here.

Changing Shapes
From a shape point of view, it's a different story. I can imagine that this would be no problem: scanning my body, sending my information with the speed of light to a distant space station, where my body gets build up from atoms that are already there. (What to do with the original me?!) I think it's my shapes that matter to me, not the atoms that carry my shape.
Our shapes constantly change under the influence of the motions of energy. Living shapes contain a great lot of repetitions, patterns, while the dead shapes are much more random of structure. Some of our shapes live on in our children: a mix of their parents DNA and what they learned from them. And also the memories of all of us: how we were, what we did, what we left behind. All the actions we do echoe on into the future, most weaken but some get amplevied.

Logic motions
If the motions in this universe are simply a matter of cause and effect
I am the effect of many motions that happened before in this universe, especially those of my parents. Everything in this universe is more or less connected. Some say that non-logical things happen at sub-atomic scale. I find that hard to believe, I think that's just because we don't understand the logic yet, but who knows -my mind is limited and adapted to a human environment.

Mysterious Emotions
Emotions are the drive of life. All decisions we make are based upon emotions. In our body there's emotion related electro/chemical activity going on, but to me that doesn't explain what emotions are. Any shape of matter is worthless without a emotional judgment. What exactly emotions are is a mystery to me. When dead, what about the emotions? Will they be gone just like how shapes decay into randomness, or will the move on like atoms do?