Death is a scary concept. The fact that one day, a day that you can't foresee, you will stop living. All your hopes, dreams, gone. The progress you've made stops. You finally return to where you came from: an infinite void of nothingness.
Doesn't it put everything into perspective?
You're going to die. You've got to be conscious of that fact. Strip away all of the romanticism behind it, and really understand the raw primal meaning behind it. You will not live forever and that means you need to make the most of the time you have now. I'm not saying live every day like it's your last. What I'm trying to say is live like you've lost your security deposit. Take some risks, but keep it in check. Pull as much meaning from each moment as you can and really try to understand your purpose here.
Everyone has a purpose in life. Nobody knows what theirs is though. Our purpose is to find our purpose in life. It sounds like a paradox, but finding your purpose is your first job, then pursuing your purpose is your next job. There's no right answer to your own purpose, or the meaning of your life. It's what you make it. It can be broad like "I want to make people's lives better" or it can be specific like "I want to win the Nobel Prize in Physics". Whatever your purpose in life is, the sense that your life isn't permanent should be a motivator to make the most of what you have.
Without death, we can't appreciate life. Without thirst, we wouldn't appreciate water. Without hunger... you get what I mean. The absence of something is what makes you appreciate the thing that is in absence. Death, the absence of life, makes you appreciate life. But we've got somewhere between 60 to 80+ years alive and, especially when we're young, we don't really keep our perspective. We're more likely to do think in a way that shows a lack of perspective, really. When you're out with friends, and everyone keeps checking their phones hoping something bigger and better will come up so they can do that; that's a lack of perspective. A fear of missing out, a real societal problem since the rise of our interconnectedness, is a lack of perspective.
We're not spending enough time in the moment. Science states that the more time you spend in the moment (in the zone, or just being present with your friends and family, for example) will increase your enjoyment and happiness. When you're not in the moment, time seems to slide by quickly. It's why you can go through a week very quickly if you're in a very set routine, but one day doing something new feels like it took a lot longer. It's why life feels so short. There's a quote by Seneca, an ancient Stoic philosopher that sums this up.
He says soft and careless living causes us to lose track of time. Soft and careless living, to Seneca, was living a life doing things that weren't ultimately important. So what was important? Doing the right thing, and living in the present. The whole library of Stoic wisdom really comes down to those two points. Death follows us, and we all must die, but we can live a long and good life by doing the right thing, doing our jobs, finding our purpose and pursuing it, and living in the moment.