What is eustress: positive effects of stress. You grow stronger, and become less vulnerable to illness or injury: explain why stress is essential to your health, without any stress, you would be bored into clinical depression. We need stress to challenge ourselves and accomplish things: discuss the current state of knowledge regarding exercise and longevity. It is difficult to gage it because those who exercise regularly are less likely to smoke. It is accepted that exercise extends life by about 1-3 years. 2: exercise improves the quality of life, describe how a regular physical activity program may slow down the negative effects of aging. You may need to look back at a few other units to answer this question more comprehensively: physical activity will increase bone density. This will reduce the problems such as osteoporosis that occur when the individual ages: as you age, muscle deteriorates causing a great loss of strength.