Resist the urge to over-medicalize things: if it lasts longer than two weeks and affects your ability to enjoy life, it may be "depression". If you get dumped by your girlfriend or yelled at by your boss and the next three days really suck, it is "life".

My brother once told me: "There is a support group for people who hate their jobs. It is called Everybody, and we meet at bars starting at about 5:30."

Adjust by about six hours and it is equally true for Japanese salarymen.