When God chooses you: "And Mary said, My soul does magnify the Lord, and my spirit has rejoiced in God my Savior" (Lk. 1:46-47).
When you know you are His: "...rejoice, because your names are written in heaven" (Lk. 10:20).
When you see God in action: "...the disciples began to rejoice and praise God with a loud voice for all the mighty works that they had seen" (Lk. 19:37).
When thinking of Christ being with the Father: "...If ye loved Me, ye would rejoice, because I said, I go unto the Father: for My Father is greater than I" (Jn. 14:28).
When you see others being blessed: "Rejoice with them that do rejoice, and weep with them that weep" (Rom. 12:15).
When others are being honored: "...one member be honored, all the members rejoice..." (1 Cor. 12:26).
When the truth prevails: "Rejoice not in iniquity, but rejoice in the truth" (1 Cor. 13:6).
When others are faithful: "I rejoice therefore that I have confidence in you in all things" (2 Cor. 7:16).
When Christ is preached: "...Christ is preached; and I therein do rejoice, yea, and will rejoice" (Phil. 1:18).
When? Always!: "Rejoice in the Lord always: and again I say, Rejoice" "Rejoice evermore" (Phil 4:4; 1 Th. 5:6).
When thinking of your relationship with Christ: "Let us be glad and rejoice, and give honor to Him: for the marriage of the Lamb is come, and His wife hath made herself ready" (Rev. 19:7).