Practice and work, nothing happens on its own. Figure out the words and sounds that trigger you. Then.. in my case, learned other words or sounds to use instead, back up a couple words and try again, just stop trying for a moment take a deep breath and try to relax then try again. Unfortunately you'll need to do this with someone else since most of us don't stutter when alone. But you can definitely work on what sounds trigger you while on your own in your own head. I've stuttered my whole life, I'm 33, it get easier over time. But really you gotta learn to just accept that it's part of you and all you can do it try your best.