Because Jesus has set me free from the corrupting influence of sin and worldliness, to serve Him and follow Him on the narrow path that leads to life, this isn't a false happiness derived from what I am, what I do and what I may own, but an inner joy coming from His great strength and power to keep me in His will as I obey Him from my heart!
Jesus didn't die on the cross to take my place or wrath, to make my life easy and fun! No He died so I could suffer with Him, and walk a life through His great example.
Now He is calling His children to walk the crucified life unto Him, through His power,which gives us the power to overcome all temptation and willful, deliberate sin against Him, which leads to death, not happiness.
True happiness begins in the heart, and having a heart for Jesus, and His truth, standing firm against the wiles of the devil, and all the false teachings coming out of the church today, giving many a false hope in a lie, that teaches Jesus did it all for me, I do nothing except trust what He did for me, and now can live life as I please, loving the world, and God at the same time, because all is well, its all been done for me. Which is a lie!
Don't be fooled, God is not mocked,
Gal 6:7 Do not be deceived, God is not mocked. For whatever a man sows, that he also will reap.
Gal 6:8 For he sowing to his flesh will reap corruption from the flesh. But he sowing to the Spirit will reap life everlasting from the Spirit.