Whatever was to my profit I now consider loss for the sake of Christ. What is more, I consider everything a loss compared to the surpassing greatness of knowing Christ Jesus my Lord, for whose sake I have lost all things. I consider them rubbish, that I may gain Christ and be found in him. (Philippians 3:7-8)
I think the key to finding true happiness in this world is found in the verse above. Most of my life, I fruitlessly sought happiness in being successful; whether it be in sports, school, or career. Unfortunately, nothing I did was ever good enough for me. I couldn't hit enough base hits, get enough A's, or make enough money. It took finding a close relationship with Christ for me to finally let these things go.
In Christ, all those things became less important, and I began to live a happier life. I find it much more fulfilling to share the joy of Christ than to be wrapped up in the pleasures of this world. Hopefully, that desire will never change - no matter what personal sacrifices that might mean along the way.