The stress I refer to here is the daily stress of life, an example troubling over how to pay of your debts. The training I refer to is training for a race etc., not merely just exercising for fitness.
How do you mix it all up? Training is to adapt to the stress experienced during a workout and recover from it. Lets say you suddenly got a huge problem at hand, like having a relationship problem. If you exercise at the same level before you had such stress, the total daily stress could become too great for you to handle. What should be done? Remove the training totally since the stress could be great enough already?