There's no need to feel bad even if you feel bad. Cut that misery loose and go exploring!

Here's some of my favourites techniques:

Lift yourself up

Go deep
I feel brilliant
Find the still point
Eat less, eat better
Using gestures to unlock different mind states
Breathe in, breathe out, release
Am I OK?
Find your heart
Life does not give us what we want just because we want it
Some feel good tricks for your lunch hour
Lose your attachment to the way things should be
Do you have something positive in your life?
How do I park my mind at night?

General relaxation

A nice exercise in body awareness
Enjoy a beautiful breath
How to calm an overactive mind

Focus on the space in your head
More methods to deal with a contracted mind
Connect with your psoas muscle

Short ones

Take a moment
Body like a mountain

 More meditative

Homebrew meditation instructions
Aim, sustain, release
Mindfulness of the body
Mindfulness meditation
Concentration / Samadhi meditation
Vipassana meditation
Identify Joyfulness