Liturgy is an "action" of the whole Christ (Christus totus). 

"The celebration of Mass, as an action of Christ and the People of God, is the cener of the whole Christian life for the Chuch both universal and local, as well as for each of the fiathful individually."
(General Instruction of the Roman Missal)

See an overview of the liturgy ministries available at St Clare below.
Liturgical Ministries at St Clare