Hello Miss Megan.
"Why can't we live forever?" A powerful and eminently human question, also one that is asked by those who have yet to live happily. It is the untested, the unaccomplished, the ones who have not lived life to its fullest, that ask this question.
I think we all go through the stage where you find yourself; standing on change and fighting to stay afloat, so to speak. Looking for some reliable foundation, the way everything changes can make it seem like life is pointless; everything that comes to be eventually passes away and becomes history, some of it is just remembered for a little longer than others, and somethings pass away having never been known. It is a very sobering feeling.
I am a roleplayer. I've always used my imagination to take my mind and my consciousness away to fantastic and fascinating places. I've read so many books and learned about so many worlds, it is very much like living again and again; through stories we follow the birth, growth and downfall of characters, nations, worlds and universes. Through the skill of reading and imagination, we can very much know what it is like to live for only a few short, empty years, or we can follow the story of things that live for thousands of eventful and imaginative years.
I have lived through more lives that I can remember. I have known the stories of fictional characters whose only notable achievement was asking a tyrant for more food, or who lived an uneventful existence until they stood in front of a tank on international television before being run down and killed. Just the same, through talking to real, living people, I have known stories of triumph from old men and women at the end of their long lives, and irrecoverable defeat from the mouths of people half my age. I've been involved in things you may have seen on the news, and I've been part and partial to things no other living person is or ever will be aware of. In only 27 short years, I've lived.
I roleplayed Highlander for almost 20 years. In that time, as I grew and matured, I had a great deal of time to wrap my mind around what it must be like to be immortal. As a child, immortality fascinated me and it seemed like a neverending adventure, free to explore life at my own pace as I saw fit. As I grew familiar with the concepts of time, I grew interested in Star Trek and concepts of time travel, there I was introduced to more immortal beings who could only bear immortality by being eternal tricksters and pranksters, but underneath their frolicking and foolishness their age quickly showed. From there I resolved to read even more stories about things that seemed to never die. I read H.P. Lovecraft and read about the cosmic horror of undying things that defied our concepts of life. I read Piers Anthony's Incarnations of Immortality and read what it was like to be the avatar of Time. I watched Doctor Who and followed the story of a thousand-year- old being from a race called "Time Lords", his existence hinged on running from the end and doing whatever he could do to help whomever he could along the way. I went on to read Michael Moorcock's "Elric Saga", the story of Elric of Melnibone. To this day, Elric remains the most tortured and tragic figure in literature. He has existed across numerous universes and always with the burden of saving someone or something, even when the very fabric of chaos and creation conspire to force him to lose everything. I have read the Dune saga by the Herbert family and read the life of characters like the nigh-immortal Duncan Idaho, who is resurrected through clones time and again, or the worm-god Leto II who lived for over three thousand years. All of these stories about which I've ranted have imparted to me at least a small experience of what it is like to live beyond mortal ken.
I have studied and pondered and dreamed about long life, my mind going from the infinitesimal to the infinite, and when I talk to those who have lived for a long time, much of what they say is the same, whether they are a real human being who is barely holding on past 100 or a fictional character who is not even aware of how it could cease to be, they all say the same thing: once you have lived long enough, you just get tired, and living well is the only panacea for the fear of death. Death is nothing to fear for those who have resolved to live well. If you choose to live happily, then it becomes easier to accept the debt that all life pays.
If you've stayed with me this far through my rant, I give you credit. I find my mind always going back to a single song by an extraordinary man. Freddie Mercury's "Who Wants To Live Forever?" which addresses your very question.
Faced with the end of his life, Freddie Mercury penned the song "The Show Must Go On", and with barely enough strength to stand on his own feet, he delivered one of the best vocal performances of his already considerable career. He delivered a message to the world that is very much the same from anyone who lives well and gets the chance to pass on their knowledge to anyone else; "Don't be afraid to die. Being afraid of dying doesn't stop death, it only stops you from living well."
As human beings, we are finite and fragile, we all die and that is a basic, fundamental, inexorable fact of nature. It is pointless to resist that fact, and the only reasonable, rational, moral thing to do in light of the fact that one day or another, we all will die, is to live well.
A powerful quote from Doctor Who states "I'm old enough to know that a longer life isn't always a better one." - It is painful to live and watch the people and things we grow to love and cherish pass away, but as long as you have a breath of life in your lungs, you hold the chance to live a better life. That is up to you and you alone to make your life worth having lived. Don't search for something else to arbitrarily assign a meaning or purpose to your existence; define your own life on your own terms and by your own deeds.
As absurd a statement as this is, if you'd like to discuss this further, my inbox is always open.