Here’s the truth. We exist on this earth for some undetermined period of time. During that time we do things. Some of these things are important. Some of them are unimportant. And those important things give our lives meaning and happiness. The unimportant ones basically just kill time.

What is important though? Isn't that just subjective as well as illusionary? Purely objectively speaking (if such a thing is possible) everything is relative, even importance e.g. what is important for me, might not be for you, what is important in 1765 might not be important in 2015, what is important on earth might not be important on the moon, etc. etc. Is saving someone's life important? Yes, to that person and those who love that person it is...for a while. 500 years from now, not so much any more. So once you find something important you must also realise that this importance is only important within (your) context. Thus making it unimportant. In order to keep it important you must believe in it. Believe it has importance, believe the context justifies the importance. So in the end aren't you just rationalizing importance and thus your reason to live?

As I see it (please correct me if I am wrong) everything we do is just to kill time. importance and unimportance are just qualifications we invent so we can avoid feeling bad.