The ideas of "eustress" (good stress) and "distress" (bad stress) were developed by Hans Selye, one of the early researchers on stress. Selye believed that a mild level of stress encouraged animals and people to behave in a more active way, while an excessive level of stress would hamper their performance.
Since then, people have drawn similar conclusions, substituting the idea of 'stress' with the idea of "pressure". Click here for a full explanation of this. Framed in this way, this is an important and valuable idea.
However, "stress" is now defined as "a condition or feeling experienced when a person perceives that demands exceed the personal and social resources the individual is able to mobilize" (Richard S Lazarus). With all of its associations of unhappiness and loss of control, it is now seen as a bad thing in all circumstances.
The ideas of "eustress" and "distress" are therefore no longer useful. Indeed, they may be harmful in that they may encourage managers to try to motivate subordinates by increasing the amount of unpleasant stress they experience. The error in this approach is clear if you remember that "pressure" is a different thing from "stress".