In an experiment to find out what would happen in a stress-free environment, subjects were placed in a deprivation tank. In a short time they began to hallucinate and have delusional thoughts. You might say they went crazy. Lacking stimulation, and needing it to function, the brain produced its own. The presence of stress isn't the problem endangering health.
Stress is the body's non-specific response to stressors.
Stressors include frustrations, conflicts, and pressures and in general terms are known as adjustment demands. Every adjustment we make in life takes its toll in stress. Yet stressors, as the deprivation tank illustrates, cannot and should not be avoided. They are essential to mental and physical health. Without the stress of learning, there would be no education.