The Wisdom Of: Dr. Jon Kabat-Zinn
Dr. Jon Kabat-Zinn founded the therapeutic approach known as Mindfulness-Based Stress Reduction (MBSR). Since it's beginnings in 1979, MBSR has grown to become an established evidence-based therapeutic approach which has helped popularize mindfulness practices in much of the Western world.
Dr. Kabat-Zinn is the founder of the Center for Mindfulness in Medicine, Health Care, and Society at UMass Medical School and has authored a number of books on mindfulness. He offers an online masterclass series for those interested in cultivating their mindfulness skills, but his perspectives and mindfulness practices can also be found online through websites such as Youtube or his Guided Mindfulness Meditations website.
On a more personal note, my favourite formal mindfulness meditation is written by Dr. Kabat-Zinn; it's known as The Mountain Meditation. I came across this meditation many years ago and I always return to it for the sense of empowerment and peace I feel when I listen to it. Unfortunately I was not able to find an unpaid version guided by Dr. Kabat-Zinn himself, but this video created by the University of Derby presents the concepts from an adapted version of Dr. Kabat-Zinn's script beautifully.