Source : Webster's Revised Unabridged Dictionary (1913)

Reward \Re*ward"\, v. t. [imp. & p. p. {Rewarded}; p. pr. & vb.
   n. {Rewarding}.] [OF. rewarder, another form of regarder, of
   German origin. The original sense is, to look at, regard,
   hence, to regard as worthy, give a reward to. See {Ward},
   {Regard}.]
   To give in return, whether good or evil; -- commonly in a
   good sense; to requite; to recompense; to repay; to
   compensate.

         After the deed that is done, one doom shall reward,
         Mercy or no mercy as truth will accord.  --Piers
                                                  Plowman.

         Thou hast rewarded me good, whereas I have rewarded
         thee evil.                               --1 Sam. xxiv.
                                                  17.

         I will render vengeance to mine enemies, and will
         reward them that hate me.                --Deut. xxxii.
                                                  41.

         God rewards those that have made use of the single
         talent.                                  --Hammond.

Source : WordNet®

rewarding
     adj : providing personal satisfaction; "a rewarding career as a
           paramedic" [ant: {unrewarding}]