The Joyful Mysteries are marked by the joy radiating from the event of the Incarnation.
This is clear from the very first mystery the Annunciation, where Gabriel's greeting to the Virgin of Nazareth is linked to an inviation to messianic joy: "Rejoice, Mary."
The whole of salvation...had led up to this greeting.

First Joyful Mystery
The Annunciation

And the angel had come to her, he said,
"Hail, full of grace, the Lord is with thee.
Blessed art thou among women." (Luke 1:28)
FRUIT OF THE MYSTERY: Humility

Pray One Our Father, Ten Hail Marys, One Glory Be, etc.

Second Joyful Mystery
The Visitation

Elizabeth was filled with the Holy Spirit and cried out in a loud voice: "Blest are you among women and blest is the fruit of your womb." (Luke 1:41-42)
FRUIT OF THE MYSTERY: Love of Neighbor

Pray One Our Father, Ten Hail Marys, One Glory Be, etc.

Third Joyful Mystery
The Birth of Jesus

She gave birth to her first-born Son and wrapped Him in swaddiling clothes and lad Him in a manger, because there was no room for them in the place where travelers lodged. (Luke 2:7)
FRUIT OF THE MYSTERY: Poverty

Pray One Our Father, Ten Hail Marys, One Glory Be, etc.

Fourth Joyful Mystery
The Presentation

When the day came to purify them according to the law of Moses, the couple brought Him up to Jerusalem so that He could be presented to the Lord, for it is written in the law of the Lord, "Every first-born male shall be consecrated to the Lord." (Luke 2:22-23)
FRUIT OF THE MYSTERY: Obedience

Pray One Our Father, Ten Hail Marys, One Glory Be, etc.

Fifth Joyful Mystery
Finding the Child Jesus in the Temple

On the third day they came upon Him in the temple sitting in the midst of the teachers, listening to them and asking them questions. (Luke 2:46)
FRUIT OF THE MYSTERY: Joy in Finding Jesus

Pray One Our Father, Ten Hail Marys, One Glory Be, etc.