What profit hath he that worketh in that wherein he laboureth? I have seen the travail, which GOD hath given to the sons of men to be exercised in it. He hath made every thing beautiful in His time: also He hath set the world in their heart, so that no man can find out the work that GOD maketh from the beginning to the end. I know that there is no good in them, but for a man to rejoice, and to do good in his life. And also that every man should eat and drink, and enjoy the good of all his labour, it is the gift of God. (Ecclesiastes 3:9-13)
And if you are not a believer, if you have never put your faith and trust in the saving power of Jesus Christ and His finished work on the Cross on your behalf; everything you do is vanity, it will not satisfy, and it will not get you into a right relationship with GOD. For that you must repent and receive Him.
Under the sun is the key to understanding Ecclesiastes, for it is a tale of worldly efforts; and Jesus, The Son is the key to understanding eternal life, for He is the Word made flesh.
Trust and obey for He calls you to Himself, today.