How can I train myself to not think about what I want to say?

How can I train myself to not think about what I want to say? I've been suffering from stuttering since I was 5, and than it went away when I was about 7, but than it came back again when I was 10 and now I'm 15 and still have it. but I've found that when I don't think about what I want to say I don't stutter at all it comes out fluently. but it's very hard to not think about what I want to say when I'm in social interactions. like I try to not think about what I want to say but than I end up thinking about it and I get pauses or I prolong it when I try to say it. Is there anyway I can train myself to say something without thinking about it?