• Compassion - be kind to yourself.  Let go of "beating yourself up" for things you did or didn't do.
  
• Curiosity - approach situations as if this is the first time you've seen them.
• Acceptance - acknowledge where you are right now.  You can still strive to be somewhere else, but first, accept how you are today.
• Non-Judgement - treat all these sensations, emotions and thoughts without the qualities of "good" or "bad".  Take a step back and see them without those labels.

This can be done laying down, sitting up, walking, at a stop light, anywhere you have a few moments and would like to recenter.  Take a few breaths, sit/stand up tall, and relax your shoulders on your exhale.  Feel your breath at the base of your nose or in your belly.  Breathe for just a few moments and focus only on your breath.  You can choose to expand your awareness to other sensations in the body.  Finally, become aware of the thoughts that come, and let them go.

With a formal practice, you set aside a set amount of time every day and consistently practice mindfulness.  Usually this happens at the same time and place each day, whenever and wherever works best for you.  This consistent practice is a lot like exercising your muscles and heart every day.  With practice, you will begin to reap the benefits.