As part of the Creed we believe in the Communion of saints, those who form the body of Christ, that is the Church. Christ is the head and we are the members.
In baptism we enter into a life in Christ, we share all the good things about Christ, such as being sons and heirs of God, we also share in His sufferings [Romans 8:17]
When one member of the body of Christ suffers, all members suffer and we must contribute with our prayers for the benefit of all.
The Church is divided in the militant Church which is all of us struggling to overcome evil and to become saints, the suffering Church which are the poor souls in Purgatory and the triumphant Church which is made of all the saints in Paradise.
Eventually we will be united in Heaven where there will be no more sufferings nor tears, where we will enjoy the Glory of God.
We should never pray alone when we can unite ourselves to the rest of the body of Christ and pray as one. In this communion of saints, we should always start our prayers in the Presence of the Blessed Virgin Mary, through her intercession and in communion with all the saints and angels. As we pray our prayers will be shared in spirit with infinite value.