The concept of mindfulness, not dwelling on thoughts and sensations that arise is quite simple, but the actual practice of mindfulness requires us to learn how to be in the world in an entirely different way. One of the best (and funniest) explanations of mindfulness and meditation can be found on the following blog posts:

Neuroscience Of Meditation: How To Make Your Mind Awesome

Neuroscience Of Mindfulness: How To Make Your Mind Happy