There are said to be nine choirs of angels. Archangels represent the different aspects of the nature of God while at the same time adoring their Creator. At the top of the hierarchy are the Seraphim who spend all their time singing in glory to God. Divine loving energy cascades through the tiers of angels down to those who are closer to us.
These angels at the lower end of the hierarchy are also working through, with and in Divine love. Everything they do for us is an act of worship. As this continuing, circulating angelic energy that passes down to us is worship, so too is every kindness that we perform on impulse without expecting a reward, given unconditionally and truly from the heart.