P.S. I used to do 300 bokken cuts every morning (although now I do 10 minutes of 'standing exercise' i.e. standing in a specific chi-gung stance with my arms out in front of me and my shoulders relaxed).
With both of these I find that you forget you are actually doing the activity and it can actually make you relax and clears your mind (though sometimes this isn't the case). Definately very much like meditation but instead of concentrating on breathing you concentrate on cutting.
N.B. did you do the same type of bokken cuts all the way through?