The Collaborative International Dictionary of English v.0.48:

Mindful \Mind"ful\, a.
   Bearing in mind; regardful; attentive; heedful; observant.
   [1913 Webster]

         What is man, that thou art mindful of him? --Ps. viii.
                                                  4.
   [1913 Webster]

         I promise you to be mindful of your admonitions.
                                                  --Hammond.
   [1913 Webster] -- Mind"ful*ly, adv. -- Mind"ful*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

mindfully
    adv 1: in a careful deliberate manner [syn: mindfully,
           heedfully, advertently] [ant: inadvertently,
           unknowingly, unmindfully, unwittingly]