One of the themes in the book of Ecclesiastes is that "without God, life is meaningless and empty". 

Happiness is dependent on circumstances. True joy comes from God and brings contentment no matter what the circumstances. (see the website for Walking in the Word - Joy Parts 1 and 2.)

We don’t find meaning in life through money, pleasure, work, or popularity. Meaning in life comes from doing things that are part of God’s purpose for us. 

To be in His will is the greatest place to be.

How do we know how to be in His will?

Simple - talk to Him, listen to Him, and read His Word!