Post Workshop Depression

Have just finished a 2 day training workshop for a big new client - the first in a series of sessions. I always find that I go through a range of emotions when undertaking these sessions.
Anxiety - in advance of the workshop: will it go well? am I prepared for it? will the delegates be nice?
Relief - the evening its all over: thank goodness it wasn't a disaster, glad the client / delegates are happy
Depression - the day after, I always feel incredibly flat, even if its gone well. It may be a combination of fatigue, stress, or simply feeling low after the high of an intense group experience.

The day after ie today, I always find it hard to move onto the next thing and end up doing menial, distracting stuff. Hence - this blog post in the middle of the afternoon, when I should be doing something more meaningful instead. Must resist the temptation of playing on the Wii.