Taking things for granted

we take a lot of things in life for granted. life itself is sometimes taken for granted for example -when joey(he is my pet dog but he was not just a pet he was like my younger brother very dear to everybody in my family ) became ill, i thought that he would get better even the vet told me that he would be fine ( i don't blame the vet for what happened next , she tried her best) i told myself "joey is OK he would get back to normal, run around and play as usual like he always did" but i was shocked when i woke up the next day morning to find him cold , stiff and LIFELESS. I stood there numb did not know what to do , first i thought i was just having a nightmare but later it came crashing down on me that it was indeed reality . that day i realised that not everybody would live long become old and die. we may be alive now but we could die the next minute by the most unlikely ways. i was travelling by auto today and i thought "what if the vehicle i was travelling in crashed into something and i died '' (i don't want to be pessimist but its possible).
we all live hoping for a better tomorrow , what if today is all we have? and we have lots of things left to do like : bungee jumping or travelling around the world or just spending one day with people you love the most. i am not saying do all that today but make sure that what we do today are the things we like so that in case we die soon we would die with some satisfaction .
then again we are humans we want to fight , have wars , kill people and become king of the world(the world by then would not have humans or any life form mind you!). i am not just talking of wars and dictatorship , i am talking of day to day situations where we fight with people , hurt them physically and emotionally . why is that we like doing all that? i don't now!(and i am a psychology student)but lets just try and not do cruel things in life because when we die people shouldn't say "good riddens ".