How can we prevent our thoughts from wandering?

“How can we prevent our thoughts from wandering? How can we learn to focus our attention on one thing?”

“The answer is that we cannot do it with our brain alone; the brain cannot control its thoughts by itself. The power to control the activity of our mind comes from the body, and it depends critically on posture and breathing.”

~ From the book, Zen Training, by Katsuki Sekida