Fenrir,

I do that too. Get all wired about something and then doom and gloom crashes my party. (so to speak)
On good days, I brace myself, use rational thinking and keep putting one foot in front of the other. On not so good days, I'm irrational and hit and miss with the could-a, would-a, should-ah's.

Once you give yourself permission you will have a good time...you deserve it!