One other thing that *might* help (and I realize it's not the kosher, traditional way so take it with a giant grain of salt from this newbie
) is (in addition to respecting the tradition and doing shikantaza facing the wall), add a short period of doing it outside.
I find, for me, I like to have a little white noise and for whatever reason, I like to "just sit" looking at water, whether it's a small pond or a big body of water. Today, I did 20 minutes sitting on a big rock at the lakeshore right at the water's edge and it was very helpful to quieten my mind chatter but without fixating on any particular thing (sort of seeing past the water, birds, etc.). Again, this isn't to say that you/I should not continue practicing the traditional method, facing the wall, just that it might be a little extra practice if you can (a small raft) as an exercise to help quieten that chatter. I think it's the same reason why I need an air purifier on at night so I can sleep, the silence is deafening and for whatever reason, the noise silences my internal dialogue. (I tend to narrate everything I do, which was worse when I lived on my own because I used to talk to myself all the time LOL Now I realize that my mother does it and it drives me crazy, so I must have picked it up from her
)
That said, I don't think this is a long-term thing and it's something that I need to work through so that I can be okay with pure silence, pure nothingness sitting facing the wall. Perhaps some more experienced people can comment. I'm so glad you brought this topic up!
D-