As I was attending the Liturgy in my Russian Orthodox church and watching people both young and old stand on the same place for up to two hours without a break, crossing themselves every few seconds, it struck me.
Every time we the laypeople, simply by attending the Divine Liturgy, are making a small sacrifice ourselves by taking on this physical strain, instead of sitting like an audience at the theatre. While standing we are also more concentrated on the mass. Perhaps the people that have been in the military will understand my point better than the rest.
Sitting, being in a relaxed and passive position, while worshipping our Lord invites sloth and pride into us. Sloth, because we are resting while we are supposed to worship and pride because we sit in front of our Lord, and those who bless us, absolve our sins, give us Communion. Do we sit when the anthem of our country plays? Do we sit when the President or Monarch enters the room? Why have we given into this secularist conditioning?
Historically, only the bishops and the Emperor could sit. The laypeople had to stand (with the exception of the sick and elderly, of course). The pews appeared in church en masse only after the Reformation as one of many Protestant innovations adopted by the Catholic Church.
So, I call on all of those that style themselves as 'traditionalists' to do so. Stand during the mass and kneel when appropriate according to the Roman tradition. Try kneeling without a kneeler sometimes, encourage your friends and family to do so as well. I can bet that if the Catholic Church forbid any kind of sitting during mass tomorrow, all of the cafeteria Catholics would fade away, because they are not willing to make any kind of sacrifice for the faith that they don not have in the first place.