Mr. Kamikase,
The measurable answer that you wanted is here in the thread.
As you see from those who are able to link their physiological condition to trading and the requirement for "recovering" from it's demands (oft cited as stress), the measure is where they reach a milestone where they cannot "recover".
You see the daily "non-recovery" processed under a more stringent heading of "taking breaks". This is an intermediate pshyiologically enforced regime (no money to trade enforcement).
There is another facet that is a measurable. The "blowout". here mental facility is lost and accounts are zeroed during a mental "freeze up".
Several neat and consistent psyiological and mental actions are in force for all of these examples. This, then, gives you a very very convenient measure for when the quitting point is reached.
Recovering on an intraday basis is just stretching out the mean time to failure. The other healthy side of doing health maintenance on an intraday basis, takes potential failure right off the table. Both these are illustrated in the thread as well.
So whats the simplest measure?
Whats the best pertinent measure?
The simplest is a non denial based personal assessment of the continuing ability to recover on a daily basis and to recognize also that a person is actually maintaining a healthy existance.
The best most pertinent measure is to assess the body's ability to be able to normally generate biochemicals for maintaining non stress long term periods and concurrently, to not over generate the "reptilian complex" of biochemicals. A critical measurement point to save time and sampling is to measure the latter complex content after an exhaustive exercise routine has been completed.
The continuing presence (and often continuing production) after extreme remediation physically is an unequivacable statement of "failure".
I waited to post here until there was a complete spectrum of examples of sucessful trading and many posts by those who are way past possible recovery. The money thing, oft cited, as you can see, perhaps, is a very lagging indicator and , if fact, a driver of failure, mentally and physiologically.
I have posted several reading locations on this and each contains a bibliography to get a lot further into it. I have an agreement to publish as a cooauthor with an authority in this field. my role is to make the connections of trading to the myriad aspects of optimizing human functionality.
To deal with the converse of failure, is much more interesting and rewarding. Several here used the word nimble. Others read it and spoke in parallel to the concept. If one wishes a quick experience of a shift in "nimbleness", from no matter what level of failure/stress/success/optimal balance, it can be done with just a couple of days of health oriented catalytic intakes. Reading, the front end of Ehdin is good for that.
To assess optimum states for trading at excellent levels, have a person who optimises personal energy and nimbleness do observations of you over time. A reiki practioner/ trainer/healer is best for this. RMT, IARP credentials after the person's name is usual. I was unotrusively observed for a couple of hours last Thursday in a "educator" setting. For whatever reasons the assessment was that the transfer of information and its understanding by the recipients was judged to have been at an unexpected limit because of the "from-observation-to-action" skills demonstrated.
My normal weight shift in a normal trading setting/session runs around up to a four pound loss while maintaining a slightly acidic normal rate of hydration and nothing else.
