Most people know that active Mormons are enthusiastic about sharing their faith, and we are actually commanded to be member missionaries. I've benefited myself from various members taking the risk of talking to me about the Church (capital C). And I'm not a shy person - I've gone up to complete strangers wearing Cal t-shirts to tell them about the alumni association.
So why am I so hesitant to talk about the Church? I have a testimony. I do everything I'm supposed to do. It's an integral part of my identity. But I'm stuck, mute, whenever a golden opportunity comes up.
I remember, back when I thought it was part of my Christian duty, feeling really guilty for not "witnessing" to people. Now that I'm more on the other side of that, I know how awful it can be from both sides. So although I know it's a personal decision, I guess this is just to say, I understand.
Feeling that something is a central and fulfilling part of your life doesn't automatically make one excited to push it as a central and fulfilling part of someone else's life. I don't know if that applies to you; it does to me. (Obviously I'm not talking about the church in my case, but other stuff.)