So many Christians are miserable, because you're neglecting the positive side of the gospel. You're not doing the negative - avoiding fornication, no longer at the false church - but you're not doing the positive of living to share the gospel because you're feasting on it yourself. You're not as evil as you were in daily action, but you're not enjoying the gospel as you should be. The First Love is gone and everything is routine. You don't laugh at the jokes and get drunk like you used to, but you don't share the gospel either, because you think it's not worth it. You've been rejected a thousand times.
We'll, we can surrender the positive side and play defense all the time, not doing this and not doing that, but it's WEARISOME and boring, is it not? Or, we can feast on the gospel, admitting that life is vain, and ask God to show us His glory, to forgive us for slinking back into sin, and to give us a life committed to one cause.
I assure you the thrill is not gone. The peace is still there, but it can never be experienced half way in. So many brethren are miserable because you don't think you need forgiveness and a full throttled mission in life. You think, "After I get married, after I have some money, after this or after that. Besides, I'm justified by faith and conduct doesn't matter." Well, if we'll be happy, there's only one way!
Do you remember how you started with Him? Hot... Amazed that He'd forgive you, telling people about the doctrine of grace. Do you remember how much joy you got witnessing, even if people turned away, and how the Father comforted you after their rejection? The devil stepped in and said, "It's not worth it." He brought up those times you failed, sinned, and shamed your profession, and now he says, "You? Live for Christ? You've got to be kidding. The hypocrite? Don't you think they remember you drinking too much? Don't the kids remember all the Sundays you slept in? How about the people at work? They'll be surprised to hear that YOU are a Christian." Go ahead and surprise them then.
I saw someone discouraged recently about another broken diet. "What good is it to start today?" She reasoned? Well, It's better than not starting, and so it is with the Christian life. Repent. Turn around right now. Get on your knees and tell Him you've failed and are miserable! He'll receive you. He'll give you light. He says, "Awake, sleep, and rise up from the dead, and Christ will shine on you." He'll restore you by forgiving you all over again, and you'll have a GREATER REASON to be happy than ever before.
Get back in the game. Don't quit. He restores the years the locusts have eaten. There's no other way.