The biggest complaint I seem to hear about from people is that there is too much stress in their lives.  Here's what Webster's dictionary defines as stress.

1.  A force exerted when one body or body part presses on, pulls on or pushes against another

2.  The deformation caused in a body by such a force

3.  A physical, chemical or emotional factor that causes bodily or mental tension and may be a factor in disease causation