You might think it's really a simple word but I have learned to think of it as a little more complicated. For instance. Have you ever been affected by someone's happiness or better yet someone's unhappiness. I could give so many examples of this just like you could but being as I'm recently married ill use my husband as an example. When he's happy it rubs off on me and when he's unhappy I can't shake the hurt in my heart for him. But beyond the immediate feelings of happiness and unhappiness we all experience what is true happiness and unhappiness?
Every question I have ever asked, no matter how small has always been answered when I open my Bible. I think the best example of happiness is found in Psalm 37:1-8 but especialy v4 'Fret not thyself because of evildoers, neither be thou envious against the workers of iniquity. For they shall soon be cut down like the grass, and wither as the green herb. Trust in the Lord, and do good; so shalt thou dwell in the land, and verily thou shalt be fed. Delight thyself also in the Lord: and he shall give thee the desires of thine heart. Commit thy way unto the Lord; trust also in him; and he shall bring it to pass. And he shall bring forth thy righteousness as the light, and thy judgment as the noonday. Rest in the Lord, and wait patiently for him: fret not thyself because of him who prospereth in his way, because of the man who bringeth wicked devices to pass. Cease from anger, and forsake wrath: fret not thyself in any wise to do evil.'
I dare you to try and find compleatly whole and content happiness without God. I know I didn't. And if you can't find happiness without God what will you have? That's right, unhappiness. With God you have everything (happiness) without God you have nothing (unhappiness).