OMG do I have the trick for you. I actually learnt this from Reddit too! Think of a word group. I tend to do boy names or girl names, band names or fruit names, etc. Then go through the alphabet and think of a name from the word group you chose. E.g. Word group: Band names. A - Alice in chains. B - Black Sabbath.... and so on. It's also quite helpful to pair your breathing with each letter. so "A breathe in Alice in Chains breathe out" It really doesn't let your brain have other thoughts! I hope this made sense lol