Acceptance, or willingness, is an ACT skill of accepting your inner experiences: thoughts, images, emotions, urges, memories, sensations. By accepting these experiences, we decrease avoidance of our experiences, and make ourselves more open to living within our values.
Why practice acceptance? Well, we all have inner experiences that we wish we didn't have. Sometimes we can cope just fine without trying to push away discomfort that comes with these experiences. But, what about when that doesn't work?
When we talk about acceptance and willingness, we are making room for discomfort, allowing it to be present, and then using our values to guide our actions. It doesn't mean we like the discomfort, or that we are approving of it. It means we stop struggling with what already is. We are letting it be, and spending our energy on pursuits that matter to us.