I can't imagine this passage of Holy Scripture not being a favorite of most Christians earnestly devoted to the faith of Jesus.
Its biblical context sounds like an exhale and a deep sigh of relief after finding a priceless treasure.
From my point of view, I see a divine principle of truth, profoundly evident as cause and effect... Delighting thyself in the Lord will cause the Lord to give you the desires of your heart.
So what does it mean to be in the Lord?
How does one come before the presence of him who is a Spirit of Almightiness?
How will your life dramatically change after being joined to omniscience, omnipresence, and omnipotence of the Supreme Being?
Will all things be possible?
Without question, it infers the new birth - being born again of the water and the Spirit. It's a divine regeneration of heart, soul, and might of earthling beingness as prescribed by God the Father according to the Holy Scriptures!
Therefore, to be truly in the Lord, you must be the righteousness of God by faith to effect spiritual regeneration that makes a sacred covenant with God the Father for eternal life and salvation.
Whosoever is born of the Spirit is a spiritual living soul - an immortal unto holiness according to godliness.
The new birth is only the beginning of a never-ending journey in the Kingdom of God. For the Kingdom of God is in righteousness, peace, and joy in the Holy Ghost with power!
I see a reward for being made the righteousness of God by faith towards our Lord Jesus Christ... Whatever things you desire, the Lord will give it to you!
It's the serendipity of a personal sacred relationship with God the Father. It is an immutable promise of never-ending eternal life with salvation. It saves you from the woes and perils of an evil world fraught with Satanic influences.
The Creator of all things good for you to desire exceeds all expectations from the sacred covenant promises of life.
For eyes have not seen, neither ears have heard, the good things God the Father has prepared for them that love him. This then is the extent to which we delight ourselves in the Lord - Love him with all thine heart, and all thine soul, and with all thine might! Love thy neighbor as thyself!
So then what are your desires of the heart?
1 PETER 3 [LJCV] ~ For the eyes of the Lord are over the righteous, and his ears are open unto their prayers.
JAMES 1 [LJCV] ~ Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.
Knowing the source of all goodness in every desire, make your requests known unto the Father in the name of Jesus whom God exalted and maketh intercession for us all.
Jesus the Lord Christ is our Mediator and Advocate with the Father. How much more will he give you all the things you desire when you delight yourself in him.