I've always found it hard too. Maybe try to figure out why, and then see if you can get around it.
In my case, I've found I struggle to say anything because I'm so concerned what the other person will think of me and if they'll misinterpret what I'm saying. For example, if they ask me what I think about homeless people (or if that's just the subject the group is talking about), I feel tense because I don't know what I can say. I can tell them what I believe, but in this day and age people are hyper-critical and will make your life a pain to live if you disagree with them. And let me tell you, there are tons of people out there who disagree with what you or I believe.
So, I've found talking is painful because I fear rejection. So, one way to solve this is I need to get over the fear of rejection, which is no small task, but it's a goal instead of not knowing what to do at all.
I don't know if that helps. Our problems are likely different, but maybe I said something helpful to someone.
Take care out there!