Tips
If you find yourself having one bad day after another, you may need to do something more. Your job might be bringing you down; you may be in danger of suffering from stress. You may even be dealing with depression. If you think this may be happening, do something, and talk to someone.
As a preventative measure, do something so that a day starts well. Get a coffee, or some juice, and sit with a friend for 15 minutes. Or, if possible, start the day with a nice walk outside, or some sort of physical workout. A good start to a day may help you to glide more easily over any bumps that come up later.
Get physical! Go to the bathroom and jump up and down (when no one else can hear), breathe very deeply, take a quick walk at lunch time (or to the gym for the kickboxing class). Get that workout. Kickstarting endorphins is a natural way to a better mood.
Make sure that you are not living on sugar/candy bars. Quickly roller-coastering blood sugar levels can be unpleasant.
There are some who, whether they admit it, or realize it, or not, enjoy being in a bad mood, and will resist all efforts to be cheered. If this is the case, there is not much that can be done, until you admit it to yourself.
Find a great song, and let it take your mind off of your present state.
Laughter is priceless. Find a funny video, e-mail five friends, asking for their best joke, watch little kids play (and watch them laugh!)
Sometimes, you have to "fake it 'til you make it." Saying, "This is a TERRIFIC day" will sometimes help you to, at least, see the possibility that it could be. THINK POSITIVE THOUGHTS!
Just smile. Yeah, you may not feel like smiling, but just forcing yourself to smile may send a signal to your brain that things aren't so bad. You may be surprised to feel your mood lighten a bit, in as little as 10 minutes (or less)!
Warnings
Don't make huge decisions when you're in a bad mood - financial ones, emotional ones, etc. Let the negative state pass, before you choose poorly.
Watch out for blaming other people for things that you, in fact, may be guilty of. If someone's loud telephone conversation annoys you completely, check out your own conversations before telling that other person.
This is not the day to "finally" let someone know what you think about him/her. This is the day to write those things down, and to get them out, but not to try to act on them, until your mood brightens.
Bad mood days can be like a downward spiral. Resolve within yourself that tomorrow will be better, and do whatever it takes to make it so.
If there seems to be a long string of bad days at work, and depression is a part of your life, check to make sure that medications are still working properly.