Here’s a gem from Martyn Lloyd-Jones’ collection of sermons entitled Let Not Your Heart Be Troubled:
“The classic statement of this was made by our Lord in his Sermon n the Mount, when he said, ‘Blessed are they which do hunger and thirst after’ —happiness, joy, peace? — Not at all — ‘blessed are they which do hunger and thirst after righteousness: for they shall be filled’ (Matthew 5:6, emphasis added). In other words, if you make happiness or joy or peace your one aim and object in life, it is certain you will never find it; but if you put righteousness as your main aim, and if you become so concerned about righteousness and true living that you can be said to be hungering and thirsting after it, well then, says our Lord, you will be filled with happiness. It will follow.
“This, I think you will agree with me, is something that is absolutely vital and fundamental. If you come to the Christian faith merely because of what you want it to do, you will never get that thing, nor will you get anything else. The Bible must be taken in its own way; it must be accepted on its own terms. There are no shortcuts once you begin to deal with God. God demands something that is central from us — He demands total allegiance. You cannot take things out of the gospel of Christ. You must take the gospel as it is without any modification or qualification. So if you want blessedness, you must start with righteousness; otherwise you will never know it.”