I was on one of my usual soapboxes the other day, and a kind commenter now wants to know what I mean when I say "orthoprax". I've never tried to systematize that before; it's an idea I grew up with and pretty much just accepted as an assumption about life. But now I'll try to make a beginning, for M.David's sake. Please comment, and help with hashing this one out!
"Orthopraxy" means "right acting" or "proper behaviour", just as "orthodoxy" means "right teaching" or "proper belief".
Catholic orthopraxy, at its core, is an internal disposition --- a determination, with God's help, to have the Faith inform every aspect of one's life, and to do absolutely everything in a way worthy of one who is loved by God. There is not the "spiritual" realm at church on Sunday and the "secular" realm everywhere else, but only a life lived in Christ at all times and places, submitted to Christ in and out of church.
In my own experience and observation, orthopraxy nearly always manifests externally in a few specific ways: an unobstentatious devotion to the Holy Eucharist, daily prayer and/or lectio outside of Mass, a willingness to do the unheralded less-favored parish chores, and, most especially, frequent and joyous commission of the Works of Mercy, which, for me, define "what Catholics do". In the Spiritual Fitness Program for Beginners, a major component is a prescribed daily act of mercy, to instill a taste for merciful behaviour and a habit of acting mercifully, on the athletic theory of "fake it till you make it."
Just how important this has always been in the Church is manifested extremely early in our history when we named the holy Eucharistic Liturgy after its final words --- "Go, you are sent," "ite, missa est." We call the Eucharistic Liturgy the Mass, the Sending service, for from it we are sent out to be the Body of Christ in the world outside and beyond the walls of the church; maybe the only contact some will ever have with Christ will be their contact with Christ in us. May we never obscure Him or put Him to shame in us.