It seems as if my outlook on life varies drastically with mood. In the moments when I feel brave and ambitious, I rarely seem to remember that it won't last: that in a week or a day, the moment will be gone and I'll feel weak and scared again—and of course it goes conversely, too.

We don't have the technology or the wisdom to redesign our own emotions. If the moments of weakness-and-fear aren't going away, and if neither mood is exactly a belief that could be destroyed by the truth, then it seems like it would at least be useful to remember, if for no other reason than to avoid wasting cognition devising plans and expectations that aren't sufficiently robust to ordinary emotional variation.