How do you build Karma from standing in cold water? My thoughts on Karma is that it is a result of actions you do that influence other things.
Certainly it is a part of karma, but not sure how you would build good karma simply from this.
I could see it as a part of a process that helps you in the three areas of mental, spiritual, and physical.
There are lots of ways to achieve the same results. For me hiking on the appalachin trail for 100KM for 5 days and not talking to anyone was a very spiritual process.
Certainly the effect it had on me, might influence the actions I took later on after it and that would translate to a karmic influence.
Shugyo is a wonderful thing sometimes. I went to Ranger School about 10 years and hoped to have a very enlightening experience from that as an extreme form of shugyo. I laughed a few weeks into the course when I learned that it just plain sucked! Not much enlightment going on.
Now the lessons I learned in the past 10 years that I have drawn from that experience have been very worthwile.
My point is I guess that standing under cold water can be a good thing, it might work for some, not for others, and for all of us, it will make us cold and definitely wet!
To eaches own!
I would be game to do it someday though, as I think it would help form a strong bond between the participants which leads to greater understanding and interdependence...which is what I think true enlightment is all about anyway....so maybe it does develop good karma after all