Is the practice of being aware of the present moment. Usually achieved through focusing on something like your breath.
One thing to realise here is that you are not in control of your thinking. You are simply an observer to whatever happens and whatever your mind produces. Sometimes it produces wonderful things but more often than not it can produce anxiety and other really nasty things that you have no say over. Unless of course you just observe them and let them pass through like clouds in the sky.
Treating thoughts and thinking in this way is incredibly freeing. Not getting attached to what you think. And not getting attached to anything really is incredibly empowering feeling. But it is something that you have to practice often.
I like to practice mindfulness through journalling my thoughts in my diary. I wrote about it here.
Although I do want to start more focused mindfulness and trying to practice channeling my focus. I do build my personal system of productivity and happiness around this idea of less thinking, more happiness. I try to cultivate good thoughts and let bad thoughts pass by. I focus on the present moment and try to take the best from the cards I have been dealt. And more importantly I try to be proactive with life. Great things won't happen if you sit idly waiting for things to happen. You either have to go out and find these great things or make your own.