This Psalm is a song of David, written as a triumphant celebration of worshiping at the house of God.
This "song of ascents" as it is called, or song of "going to Jerusalem," was written because David was so joyful - glad - to be going to the house of the Lord.
Not only was he happy to be going, but he was happy to be asked: "I was glad when they said unto me…"
The things we see here are the love of the house of God, in a community of believers, both passionate for God and for the rest of the group.
When we go to worship God, do we really worship? Is our church a house of worship? First and foremost, we acknowledge God. This is usually done through songs or words which emanate from our heart.
The heart of the matter is a matter of the heart.
Do you love God passionately enough to take pleasure in His house?
The worship for Him; the mercy of Him; the Love that is Him.
The next time you go to church, keep in mind that if you love Him, really love Him, then Joy would bubble up whenever you think of Him. We should love the whole scope of His personality: all of Who He Is.
God Is Good and we should celebrate Him whenever (like David) we can be in His presence. In His presence there is fullness of Joy.
Celebrate Him this Sunday, and bring a friend.