A study shows that employees, who did exercise on work days, become stress free, happy, more efficient, calm and productive. Researchers conducted the study on 200 people at the Bristol University, included university staff and employees working for a pensions firm and an IT company. Everyone completed a questionnaire about their mood, workload and performance on days they exercised. Researchers found that employees who exercise during lunch breaks – improved their concentration, felt more energetic and calmer and better equipped to handle the problems.