Many people get a lot out of meditation and mindfulness. The thing is, the sturdier we feel emotionally, the better our speech gets. Or maybe rather I should say, the less bad we feel, the more fluent we are. Stress and anxiety can make a stutter worsen, or become more visible. Things like mediation and mindfulness are meant to put you in a more comfortable headspace. They don't cure your stutter. They don't even 'help' your stutter. But they can make you feel good, which may lend your brain some energy to possibly overcome a disfluency. In any case, they certainly can't hurt ;)