Health and Eternity
The question we should be asking is 'Who is allowing it?' Is it fate, or destiny? It is punishment for past sins? Are we being taken now, because we may have become a bitter or cruel person later, had we been allowed a full life? No, it's not actually any of these reasons.
To understand this better, we have to back up and look at the big picture, a much bigger picture than what we may be used to seeing. For starters, remember that we are each an eternal spirit, passing through a relatively short human lifetime, and most probably returning to repeat the adventure more than once. Basically we are a piece of eternal magic, driving around in this shell we call a body, complete with ego and a mind and other attributes. The body is temporary. The spirit is eternal. As humans, we too often forget about who we really are as spirits.
So, suppose you were to go on an adventure as a spirit. You might think it challenging to live in a human form and forget about most of your spiritual powers and capabilities. Almost like going on a thrill ride at an amusement park, we get scared, surprised, frightened and more - because it's fun and we have an inner desire for adventure. As humans, we create suspensful and scary movies, and we like to try and figure out the stories despite our fears in watching them. We may choose to read scary or tragic books, once more being greatly moved by the experience. As spirits, each of us have already come here, perhaps having chosen or planned our path ahead of time, giving us the feeling of fate or destiny once here.
So here is where it gets interesting. What if our challenge was to face death and war and other horrible things, yet to continue to be positive and hopeful? What if we inspired others with our hope? Would that not be both an adventure and a challenge? There is a risk that we'd become bitter and hateful, but we might also experience amazing growth and become happier and stronger by going through the experience. Our attitude, based on our free will, is the determining factor. Now, instead of a war, let's make it our own mortality that is on the line. This is where illness comes into the story. What if we chose to live this human life and succumb to an illness, yet with our joy intact? Our love, our positivity all intact? What an inspiration that would be. We would also have had the ultimate adventure, and won the ultimate challenge. None of us get out of here alive anyway, so if we are cut a bit short in time, but it brings us great eternal benefit, then its not entirely a bad thing.
Let's all remember who we are and why we're here, and hopefully we'll live long lives while growing in love, in patience, in joy and all of the other eternal things. But if ours or a loved one's life is cut short, they are simply going back to eternity a bit sooner, and still very much alive.