Exercise makes people happier, a new study has found, especially after a really bad day. Researchers say that satisfaction with life greatly improves in people who extend exercise routines on days when they feel low.

"We found that people's satisfaction with life was directly impacted by their daily physical activity," said Jaclyn Maher, Penn State graduate student in kinesiology.

The study included men and women between the ages of 18 and 25; period in life when people are most dissatisfied with their lives.

"Emerging adults are going through a lot of changes; they are leaving home for the first time and attending college or starting jobs. As a result, their satisfaction with life can plummet. We decided to focus on emerging adults because they stand to benefit the most from strategies to enhance satisfaction with life," said Maher.

Study participants were divided in to two groups; first group had about 190 people who had to make a diary entry every day for 8 days while the second group that had about 60 people who had to make an entry in a secure website every day for 14 days.

Participants were assessed for their personality and had to take questionnaires that asked them about their happiness levels and how satisfied they were with their lives. Their levels of physical activity were also assessed during the study. 

Researchers found that extending work-out sessions helped people become more satisfied with their lives.

"Shifts in depression, anxiety and stress would be expected to influence a person's satisfaction with life at any given point in time. In addition, fatigue can be a barrier to engaging in physical activity, and a high Body Mass Index associated with being overweight may cause a person to be less satisfied in a variety of ways," said David Conroy, professor of kinesiology.

A recent study suggested that older men and women, even those around age of 70, can exercise and keep dementia away. This study had found that physical exercise, and not just mental, helped people stay off dementia.