The Emwave Personal Stress Reliever from Heartmath

Pros: Relaxing, well-designed, rechargeable, lots of options, good instructions.
Cons: Visual feedback works but would benefit from a more capable display.

EmWave is a well-made and interesting product that so far has given me good results. It gives you visual cues to use in regulating your breathing, which helps counteract stress or tension. Perhaps a nice meditation break under a tree would do just as ...