80 It is, therefore, desirable, Venerable Brethren, that all the faithful should be aware that to participate in the eucharistic sacrifice is their chief duty and supreme dignity, and that not in an inert and negligent fashion, giving way to distractions and day-dreaming, but with such earnestness and concentration that they may be united as closely as possible with the High Priest, according to the Apostle, "Let this mind be in you which was also in Christ Jesus." And together with Him and through Him let them make their oblation, and in union with Him let them offer up themselves.
Source: Mediator Dei (Vatican.va)