I'm 27 and started stuttering when I was 3. I've found a lot of success with Lee Lovett's book "How To Stop Stuttering & Love Speaking". Now I can truly say, I never have to stutter in any situation - I can always pick a certain speech tool to go around it. And nowadays, the blocks/hesitations I've been facing have gotten less and less. It really feels like I'm "unlearning" to stutter day by day. Can heavily recommend.