Reflection versus rumination
Few will argue that awareness and insight leads to better decisions as well as personal growth. We all need to regularly step back from our busyness to ensure a healthy work-life balance and prevent potential burn-out as well as so-called tunnelling, when we're only able to concentrate on the immediate and urgent matters in front of us.
Reflection is a powerful activity to provide clarity and perspective, awareness and a longer term view. It is different from introspection, which can turn into rumination. Rumination and questioning yourself can be disruptive and give a sense of loss of control.
Rumination often follows when asking repeatedly the question 'why'? 'Why did that happen to me, why do I feel like I do, why did I get that wrong?'. By all means start with why to establish a purpose, to make decisions going forward or to diagnose the reasons for what happened.
However, to increase awareness and personal growth, a more beneficial question is 'what?'. "What happened?'; 'What did I think or feel and behave like when it happened?'; 'What can I learn from this?' and 'What will I do next (time)?'. Reflecting by using those 'what' questions support personal development and growth and improve performances over time.