Claudia Hammond finds out why your exercise regime could be hindered if you have been taxing your brain too much. She talks to Professor Samuele Marcora from the University of Kent about his research on why the chemical by products of being mentally exhausted can actually make physical exercise much harder. He discusses his new research with the Ministry of Defence where he is finding that soldiers can be trained to resist the overwhelming effects of cognitive fatigue. Also in the programme the moral distress experienced by nurses and more results from the BBC Stress test and what it reveals about mental well-being.