Read this article on employee engagement which has some interesting comments. Often we have employees with strengths which aren't utilised. Managers need to help them find and develop these strengths. An employee developing their strengths and having new opportunities is usually happier, more motivated, more productive and more likely to remain with the company.
Wages often form a large portion of the costs of a construction project so even an improvement of 10% in productivity can have a dramatic affect on the contractor's profit margin.