Mental illnesses such as depression and bipolar disorder are highly prevalent and disabling. A mathematical/computational model for mood disorders (e.g., depression and bipolar), and one therapy method, are briefly overviewed. Then, key components of mood dynamics are analyzed: (i) “mood traps” (equilibria and stability), (ii) "mood-congruent attention" (stability and boundedness), and (iii) "mindfulness practice" as therapeutic attention re-balancing (stability, distraction rejection). Finally, an overview of how these can be used for the development of technology for treatment, and psychoeducation, via bio-signal-driven (e.g., via EEG) adaptive music and virtual reality (i.e. feedback control).