Jesus instructed His followers before His ascension back to heaven to wait in Jerusalem for the promise of the Father which was the Holy Spirit baptism (Acts 1:4, 5). He told them that they would receive power after the Holy Ghost came upon them (Acts 1:8). They were faithful and obedient. They realized they would never be able to make it without this promise being fulfilled.
And what a difference this made in the disciples of Christ. We no longer read where they argued about who would be the greatest after this. After the Holy Spirit came on them in Acts 2, they were different men. All the things Jesus had taught them now came to their remembrance by the Holy Spirit. They overcame fear and preached boldly the resurrection of Christ. Only weeks before, they were hiding away in a room that was locked for fear of the Jews.
Their cup was running over because the scripture says they were full of joy and the Holy Spirit. Acts 4 tells us they were full of grace and boldness. The Psalmist says in 23:5, “…thou anointest my head with oil; my cup runneth over.” The same can be true for us and the same provision is there for us as it was for the disciples. The Good Shepherd says in John 7:37-39 “…Jesus stood and cried, saying, If any man thirst, let him come unto me, and drink. He that believeth on me, as the scripture hath said, out of his belly shall flow rivers of living water. But this spake he of the Spirit, which they that believe on him should receive: …” This is how our cup runneth over. Are you thirsty? Come to the Good Shepherd and drink.
Let There Be Life 