I'm so sorry for you that this thread has become so complicated.
Here is a Wiki article on the subject of "Flow" in English which addresses all of your questions, I think. At the bottom is a long list of reference articles you can read:https://en.wikipedia.org/wiki/Flow_%28psychol...
Your original two sentences, first in German and your second in English mean slightly different things, technically.
The German sentence literally means, in English:
I am completely "self-forgotten"
. In other words, I am in a state where I am unaware of myself or I have forgotten myself, my body, etc. This statement does not say whether
I am aware of anything else
, one might assume that unless you are unconscious, (d.h. völlig unbewusst),
you are aware of something
, so the statement implies this: "I am focused so completely on something specific other than my body and my own thought process, that I am not aware of my body or even of my own existence, my self."
The English sentence you wrote says something slightly different:I am completely lost in thought.
This means "I am not aware of myself"
. My mind is completely occupied by thoughts.
However, "in thought"
is very unspecific. It could mean that my mind is drifting from thought A to B to C to D, back to A, then to D and to G. In other words, it means that I am "selbstvergessen"
but does not
state that one's attention is focused on one specific activity, intention or thought
. It could mean "I am lost to myself, but my mind is drifting."
This is not the same as being "in the flow"
or "in the zone."
.. which, by definition, means total occupation with a specific activity or task.
Being "in the flow"
requires two conditions: "Selbstvergessenheit"
AND "complete focus on a specific activity or task."
If I say any of the following, however:"I am completely lost in this activity.""I was completely lost in this activity.""I became completely lost in this activity."
All of these clearly state both conditions. Please understand that the word "in" could be looked at as "into".. German + acc. or "hinein". Please forgive my imperfect German, but if I might try a translation:Ich habe mich in diese Tätigkeit völlig verloren. Und bin zwar dazu dermassen hingegeben (worden), dass ich total selbstvergessen (geworden) bin.
Here are two other ways to say this nicely in English:I was completely absorbed in the activity (or task).
...This means literally and very graphically in German:Ich wurde von der Tätigkeit völlig "eingesaugt".
or:I was completely engulfed by the activity.
...buchstäblich:Ich wurde von der Tätigkeit völlig "verschlungen".
Allen diesen Ausdrücken liegt es nahe, dass man ja selbstvergessen ist, da nichts von dem "sebst" zur Selbstbeobachtung übrig wäre.Caveat: I am a non-native German speaker. Please don't assume that my German is to be taken as correct.