how does mental fitness afect your body fitness? :)

Question: how does mental fitness afect your body fitness? :)
- Keywords:
  body,
  fitness,
  mental
Asked by gingers to Helen on 16 Jun 2011.
- Helen O'Connor answered on 16 Jun 2011:
  
  Hi gingers: that’s a really good question (and its a big one!)
  
  Scientists are discovering that what we think or how we are feeling can affect our body in lots of ways. For instance, they have found that when we are stressed, anxious, afraid or sad, this can have an effect on our immune system (our blood produces less of the T cells we need to fight infection). The good news is that by learning to cope with stress or anxiety (by learning some relaxation techniques for example) we can also boost our immune system.
  
  So this is one really important way what we feel can affect our health and fitness.
  
  In sports, athletes use positive thinking and imagery (imagination) a lot to help boost their performance: Just something simple like saying to yourself “I CAN do it” is always going to be better than thinking “I CAN’T do it” because the body seems to act as if those words are true.
  
  Being mentally fit can also help athletes who have an injury because being positive about getting better (rather than being angry that the injury has stopped them playing sport) has actually been shown to improve recovery from injury.

Question: how does mental fitness afect your body fitness? :)