If we begin to observe ourselves and our reactions to experience, we may notice how impacted we are by our perception of others' approval or validation on the one hand, and their criticism, disapproval or rejection on the other. This can make for quite a rollercoaster ride when we care deeply, but are not fully present to the subtle workings of the mind. Mindfulness can help us have greater equanimity in the face of praise or blame.
There is an unending interplay of complex circumstances behind any given situation and we may never be able to work out completely the confluence of factors that allow certain events to germinate. A mindfulness practice helps us understand and remember this, which in turn allows us to remain open to experience. We see things more clearly and make time for consideration of a skillful response rather than being caught up in strong emotions arising from interpretations and expectations.