The problem is that many people are too optimistic about their health, ignoring the risks they face. This means that participation in workplace exercise plans tends to be low, around 7% in the sample studied by RAND. Firms are not the only ones that can encourage a healthier lifestyle; friends and families are likely to be more important But businesses can play a bigger role. If RAND is right, this may bring them financial benefits. Company taskmasters may yet grow fond of an adapted saying: mens sana in corporate sano.