@Coloma does have a point—one of the most important landmarks in any meditative practice is when the meditator is finally able to let go of concerns about technique and how good or poor one’s meditation is. Those concerns are the work of the discriminating, measuring aspect of the mind. That aspect has its place, but it works at cross-purposes to the meditation since meditation engages the non-discriminating, accepting aspect of mind. Far more important than any technique is the amount of heart one puts into the work, whatever form that work might take.
I’ve found it very helpful in my own practice to learn more about the nature of attention, considering that most forms of meditation are exercises in using attention in various ways. There are two broad categories of attention: “focused attention” and “open monitoring”. Both are useful, and the various meditative practices will aim to develop one or the other of these modes.
‘Focused attention’ zeroes in on a specific point of focus to the exclusion of other things competing for the attention. This is an effortful, will-driven task, because the brain has to actively suppress the competing stimuli. This suppression mechanism has its limits. Eventually, it gives out from sheer fatigue, and the focus is lost. This mode can be strengthened through exercise, which is what breath-centered practices aim to do.
“Open monitoring” is a throwing open of the doors of attention—pure receptivity. In this mode, nothing is excluded from the attention, but neither is anything allowed to ensnare the attention. Stimuli just flow freely through the field of attention without reaction (grasping or aversion). This is, ideally, an effortless form of attention, since nothing is suppressed. In practice, though, we find that we’re constantly and habitually reacting to this or that thing in our field of attention and allowing the attention to get hung up in those reactions. Some meditative practices, like Zen shikantaza, develop the ability to not react.
We need both of these modes. Most meditative traditions have forms of meditation that develop both. And most recognize that, in the end, these two modes are not as different as they look. Either one, pursued to its full extent, leads to the other. That is the meaning of “one thing is all, all things are one”.