Isn't it all about what you expect?

If you expect the outside temperature to be 70 degrees and it is 50, you think it is unseasonably cold. But, if you expect the outside temperature to be 30 degrees and it is 50, you rejoice that it is unseasonably warm. So you see, its all in your expectations.

Is this where people get the idea to expect little so as not to be disappointed and be forced to adjust downward? I think might also be where this saying came from. "You might as well shoot for the moon because you're bound to land among the stars."