What Burn Out is Not

In studying burn out I came across two other words that are related, but are not burn out.  They were stress and depression.
It was really important to me that I did not see a symptom and immediately assume I was suffering from too much stress or had depression.  I have experienced much of what I saw, but diagnosis was better done by those who study such things, and by more than one to confirm something or otherwise.  I saw two doctors about what to expect with my stroke.  I had no doubt both were well meaning, but it was too important to me that it was gotten right to rely on one source and run with it.
I was amazed to see there is an American Institute of Stress (AIS).  I saw that when I was looking for a definition of stress.  There is both good and bad stress.  I have experienced good stress when going for a run.  I sure did not feel like it but found after it I felt really good.  Apparently good stress produces chemicals that help.
It seems stress can be seen as undesirable.  Some resent it.  I remember the scene in the original version of H G Well’s The Time Machine where someone was drowning and no one even thought to help.  They were living a stress-free life.  Nothing was going to disturb their tranquillity.  It may be stressful, but I want to be helped if I need it, and I want to help another if it is in my power to do so.
The AIS site would not ever provide a definition of stress.  They indicated its first usage ignored the positive results it can bring.  They said “if you can’t define stress, how can you measure it.”  They quoted its current definition as proposed by Hans Seyle in 1936.  “the non-specific response of the body to any demand for change.”  The Free Dictionary was just as vague “an organism's total response to environmental demands or pressures.”  To me the Merriam-Webster dictionary was vague as well, “one of bodily or mental tension resulting from factors that tend to alter an existent equilibrium”
All I know is there is good stress and bad stress.  Bad stress is responsible for burn out.  It is seen as long term stress. 
Depression is different.  If experiencing it, help should be sought at the first available opportunity.  It is “a mood disorder that causes a persistent feeling of sadness and loss of interest.”   Untreated, depression can cause lasting issues that include employment problems, strain on relationships, drug and alcohol abuse and suicidal thoughts or attempts.  Often it is a feeling that “the world would be better off without me.”  It is not true, but the person thinking it believes it.
Some of the other symptoms of depression include tiredness, trouble focusing or concentrating, unhappiness, anger, irritability, frustration, sleep issues (too much or too little), no energy, craving unhealthy foods, anxiety, and isolation.
All of these can be a part of burn out but are not burn out.  Depression and burn out can both be caused by unmanaged stress.  I reckon managed stress is good for me.  Unmanaged stress is not.  Part of my “do it now” thinking is so I can avoid unmanaged stress.  There seems to be few things worse than thinking “I can’t do that because this is still to be done.”
To me that is run amok stress.  I don’t need it.  There are enough big stresses out there without me adding to it.