If we understand and accept the fact that we are not a permanent fixture on mother earth then we will surely lean of temporary superficial goals in our life.Our goals goes from superficial to spiritual from early on. So its better to decide from the very begining that we will die and then think what will be worthwhile to do when we are alive. This helps us in valuing our time on earth. We will look more to develop our mind through spiritual practice rather then wasting our time on distractions like Endless talking, gossiping, sports , war etc.
If we think that we will not die then we are more prone to putting of spiritual practice and wasting our time on trivial pursuits rather than making good use of our time. Pursuit of physical happiness only might not be the best use of our time. Physical comfort is just temporary absence of problems like diseases or any body discomfort ( For e.g feeling cold)
Again going overboard might not do us any good when it comes to pursuit of physical comfort and happiness. So food is needed to sustain our body. But when we eat too much food we tend to bring in a hoard of other complications like Heart disease and Obesity. So its important to have a balance so that we can achieve Happiness of mind and heart and not just of our physical well being.
One of the chief reasons that destructive emotions like Lust , Greed, Hatred arise is that we are attatched to our current flow of life. We live with a sense that our life will last forever and we become fixated on materialistic things. To overcome this foolishness we need to reflect on the fact that a day is coming when we will not be there.
The maximum amount of time we might live will be around 100 years. No matter how many years we live ultimately we all die. And this can happen anytime. Just as time of birth can never be predicted, the time of death can never be predicted too. So no matter how rich we are, we can never take the money with us when we die. In this aspect the death of a rich person, poor person and animals is the same.
Even though there is no certainty we might die immediately, cultivating awareness of death makes us appreciate life even more. If we cultivate awareness of this, then we start focusing on emotions which brings out the goodness in us rather than destructive emotions which brings out anger, lust and hatred in us. Furthermore being aware about the uncertainty of life, we will refrain from doing something which does harm for the present and he future.
This awareness helps us in shaping our thoughts and actions which will be beneficial in the long run. By contrast if you start thinking that you will be permanent fixture in this universe , then you will start spending time on matters that is superficial which will be a great loss . So being aware that one will die will ensure that we enough good will during our temporary stay on mother earth