Defined as distinct steps, but considered as leading to or supporting each other. Right mindfulness defines the environment in which mental happiness arises starts the process of deep concentration (or single mindedness citass'ekaggata):
Here is a link to a more experiential summary of this psychological interplay between effort->prolonged attention through retention (aka 'mindfulness', lit. sati) -> concentration:
"Samma-satissa samma-samadhi pahoti" - In him who has right mindfulness, right concentration progresses. [http://www.bps.lk/olib/wh/wh171-p.html#T119]
Here is a link to a more experiential summary of this psychological interplay between effort->prolonged attention through retention (aka 'mindfulness', lit. sati) -> concentration:
http://theravadin.wordpress.com/2010/09/30/surfing-on-the-wa...