The high school years were the worst for my stutter. As a grown up I've learnt to always work at reducing anxiety in general and I exposure therapy myself by putting myself in situations that are bad for my stutter regularly so they stay a dislike, not a fear or phobia. When I notice my stutter is worse then usual I take a few minutes a day to meditate and just focus on breathing slowly and relaxing. It's an accumulative affect but it does help me. Hopefully it helps you.