A five minutes trick:
What we're feeling depend on what we're thinking, this knowledge give us a remarkable control on our emotions if we want. How we can use this.
You can make a list of resources to use when you feel bad.

For example, you can read something light and amusing (I adore Asterix and Obelix). Remember that something on the kind of Ana Frank diary won't make you feel better.

Remember something /somebody nice (for example, my son Diego is very thicklish and his laughthing is really contagious, only remember it makes me to laugh; my husband, lovely man, use to buy me a rose sometimes, I love them, and even if he consider the flowers are something useless he buys them to me because he understand I adore them).

Listen to music something that makes you feel better not worst. (For example, to me there is a song of Mecano (spanish group), it's a salsa music (Bailando Salsa), the letter is very funny and the music is move, I always finish laughing)

Watching something on tv, something that makes you laugh, The bridges of Madison county maybe not a good idea, something more in the line of In and Out, Meet the parents....

If we exposed to something sad we will feel sad, if we exposed to something funny we will feel good. It's interesting to chose what we want to exposed to because if will affect our mood, the kind of people we use to be, if we are always with people pesimist and complaining we will feel that way and will have to strive to feel in another way, if we're always watching on tv bad news and fights, how we will feel....
At least be concious....