Mindfulness involves resting our mind in a place where there is no anxiety, no fear. In fact, in that place we find the opposite. We find resourcefulness, courage, and a quiet happening. Where is that “place”? It is not a geographical location. It is not a location in time. It is the flowing time and place of the present moment. Anxiety is fuelled by thoughts of past and future. When we drop those thoughts, we drop anxiety and find ourselves at ease.
Jan Chozen Bays, How to Train a Wild Elephant
Mindfulbalance 
This is similar to fasting for a day a week, to let the digestive system rest, repair, cleanse.
The ego is always flooding is with thoughts, complex things going to fast all the time. When does the mind ever get a rest. Then there are emotions that fire us up and make us avoid and dissociate.
Mindfulness as far as my personal experience goes, has no bounds what it can do. We can accomplish things thought impossible with ease when we are totally in this moment.