How to think about your past properly
When we think about our past behavior in the imperfective (e.g. what we were doing), we get better in recall it or repeat this action in future.
If you want to perform at your peak, you should carefully consider how you discuss your past actions. The way a statement is phrased (and specifically, how the verbs are used), affects our memory of an event being described and may also influence our behavior.
The authors surmise that when we think about our past behavior in the imperfective (e.g. what we were doing), we tend to imagine that behavior as ongoing (and not completed yet). This enables us to easily think about what went into that behavior and may help us improve performance on similar tasks in the future.
Interesting what if you want not to do something you can describe it in perfect form.