According to Osho, witnessing means remaining aware of the mind—the accumulated past and imagined future, the sum of experiences—without identification. In pure experiencing the mind is absent, so there is no witness; trying to witness breaks the living moment and turns it into experience. Therefore, witness thoughts and memories, but when life is happening, simply be in it.
Watch your thoughts like a movie, but when you’re actually living a moment, don’t step back to watch it—just live it.