Honestly I don't know what exactly triggered the improvement, the only changes I've been doing for the past months were: I was on finasteride(1mg) for hair loss, don't do this unless adviced to by a MD. Sing different songs with emphasis on their lyrics, especially fast tongue twisters. My worst stammer was on the phone but I still made calls, so don't relent to speak. Try talking and pay attention to your lips, tongue and teeth, I noticed when I started speaking clearly my lips were moving in relation to all sounds the word would make. Do math, technically I've been studying for an dev job and have been learning logarithms. Oh, and do things new to you or learn new skills like juggling or using different hands to brush. Read a lot and read out loud. Dont care how you sound, if you think you sound wrong, say the word again. That's it, god bless, that's technically what I've been doing and started noticing I could speak without stuttering and just 1-3 second blocks.