In what way do you mean mindfulnes? The buddhist or Zen sense? Its pretty complicated, particularly to a western mind and I'm convinced that the essential truths dont travel well and much is lost in translation, besides mindfulness there's two other concepts which accompany it which are often ommitted which are wakefulness and watchfulness.
Often when people in the west think of mindfulness they are thinking of the state of "no mind" or overcoming over cerebration, ie getting out of your head, not over thinking, bridging the mind body dichotomy which exists massively in the western psyche. So perhaps it could be considered that a particular type would have advantage or greater fortune, however they would have to strive less, therefore could not experience the same satisfaction with success or progress.
There is a western sense of this word, neuro-psychology has developed a common language with much of zen too but the meanings are a little different, an attachment and attunement meaning of mindfulness would entail the extent to which someone has developed a comprehension of others thoughts and likely reactions on the basis of an internalised "theory of mind" which has then become hard wired.
In the later western sense no type would have greater or lesser fortune in mindfulness, its a matter of genetic inheritance and family cultural acting in a deterministic fashion upon the growing individual.
however, I constantly keep a running commentary of what I'm doing in my head... like narration on Whatever TV or something... I suppose if I worked on it I could shut it up, but I really don't find it to be much of a distraction 
