I definitely agree with hattiebod in a sense but without speaking about Christ, some may think you've made a positive change in your life, nothing more, or may be afraid to ask. My dearest friend said she noticed a change in me a year or more after being saved, and only mentioned she noticed when I brought up Christ in an afterlife conversation. Sometimes you need to reach out with a direness, an urgency. Know without Jesus these people are going to hell, for all have sinned and fallen short of the glry of God. By all means, speak through action, but sometimes you need to speak through words. Really, I am not perfect and need to work on this a lot, but I know this as true, or at least my take on witnessing. As long as you follow where the Holy Spirit guides you, you'll be fine. Pray and go where God leads.