Recently while on a painting job I let the book of Ecclesiastes play on my Bible app on my phone. Often times people think of this book as depressing (vanity of vanities, vexation of spirit, etc.). However, I believe the point the writer is making is that all the labor an toll of man is meaningless and in vain if we don’t master the one thing he leads us to:
Let us hear the conclusion of the whole matter, Fear God, and Keep his commandments: for this is the whole duty of man. For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil. ~ Ecclesiastes 12:13-14
Everything in this life truly is vain if we do not live with pleasing God as our motivation in life. Without this everything we do is in vain.