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]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "mindfully":
   absorbedly, advertently, assiduously, attentively, cannily,
   carefully, cautiously, circumspectly, considerately, devotedly,
   diligently, discreetly, easy, engrossedly, gingerly, guardedly,
   heedfully, industriously, intently, interestedly, judiciously,
   lovingly, observantly, painstakingly, pawkily, preoccupiedly,
   prudently, raptly, regardfully, sedulously, solicitously,
   tactfully, tenderly, thoroughgoingly, thoroughly, thoughtfully,
   well-meaningly, with attention, with care, with caution,
   with great care, with interest, with rapt attention,
   with undivided attention, without distraction