Don't wait until December 25 to wish someone a merry Christmas. When you do, do more than give a card, present and well wish.
While I am not great fan of cliches, the Christian culture mantra of a few years back, "What Would Jesus Do?" is worth applying in some form. A more practical phrase is, naturally, "What would Jesus have me do?" The question is hard, and with Christmas approaching, cannot be ignored by those us who claim faith in Christ.
Today, December 11, is exactly two weeks before December 25, but God is not less present now than He will be.
There are obvious, easy ways of living out a Christian life in the moment, like helping at a homeless mission. There are harder, more quiet ways of the application too. Try loving your neighbor. Your next door neighbor. If you live in an apartment complex, you might have a bunch. Take them to to dinner, bring them a homemade dessert, or just stop up to say hi.
Before you get on about how you think they should do this to, remember love is not passive, but proactive. Besides, you know the verse, 1 John 4:19 "We love, because He first loved us." If you were waiting around to be loved, and call yourself a Christian, get going. Jesus has been there, done that, and is still doing it.