Not many of us use introspection, but by observing our own mental and emotional processes, we will start to recognise our thoughts and feelings. We will then begin to recognise the feelings that are making us unhappy.
We can increase our wellbeing by accepting that we may have negative feelings. By accepting we may be feeling unhappy, angry, or disappointed, we can reduce our stress.
Also, by accepting and recognising our feelings, we intentionally remove our thinking from the unconscious part of our brain to the conscious part, the reasoning part of the brain, so that we get to deal with those emotions.