The sun is what makes the cycle of nature go around. We can see the sun. We have proof that it is there and what it does helps the environment becuase experiments have been made.
and one more thing....
How do you know where you came from (before birth) and that you will go any where (after death)? There is no actual proof of it. Just what people say. People do tell lies. What if they are just lying to excite your imaginition? Say something to make it seem like there is a point in life, besides fulfilling the cycle. To give you something to do. IMAGINATION! It can be all made up by one individual.