Roz Dieterich made a wonderful observation in the discussion on Osmosis, Conversion and Catholic Culture? that I wanted everyone to see:

Fr. Mike's observation on the often-missing elements of effective "silent witness" is important. In my view, too few Catholics are themselves fully converted (in the sense that our lives have been changed to be fully centered on Christ) nor are we often in the midst of true Christian community. In that situation, it's not likely that we would radiate the joy that would cause others to desire it, nor would it be comfortable for us to express our faith to others in a natural way.

If our love for God becomes stronger than our fear, it will be much more natural for it to be expressed in our interactions. If not, being open about the things of God can seem artificial and make us self-conscious, as though we're walking around in our underwear.

Some of the most powerful instances of witness I've seen have included things like asking the other if it's all right to pray for their difficulty, gently inquiring whether the other person has considered the possibility of a loving God, or even a remark such as "It seems you have a non-negotiable assumption that there is no God. Is that true?" Each of these, in the right situation, could leave the door open for a comfortable and effective conversation if the other person is interested.

The question we should ask ourselves ought not be "Do I really have to talk about Jesus to others or is it enough for me to just try to be good?" Instead, it should be, "Since God has brought me into the kingdom of his Son, is there any action I can take that will cooperate with His desire to share himself with the people in my life?"