Lack of self-indulgence and self-pity; he does what he does gladly, following his Master by choice, not just as demanded by circumstance.
It means carrying your cross is not just one big sacrifice that you make, then you’re done with, like giving one of your kidneys, or selling your house and giving to the poor or that time you ran out in traffic and pulled the kid back from the bus.This is something you do every day. So it’s a thousand or ten thousand daily sacrifices, a lifetime of little loving acts, which cumulatively become huge.
It can be a temptation, living overseas, to feel like we've already made our sacrifice just by getting on the plane and leaving our families behind. That will only lead to the self-indulgence and self-pity that Mr. Alcorn mentions.