If you asked most people how to get a fitter, healthier brain they'd probably talk about doing brain training exercises or Sudoku.
But it's actually just as important to make your brain physically healthy, as it is about giving it mental stimulation.
Twenty minutes of vigorous activity on three or more days a week, or 30 minutes of moderate activity on five or more days a week, will reduce your chances of getting Alzheimer's by around 20%.
Even in the short-term it can have a huge effect on how your brain functions.
You know that feeling at the end of a really busy stressful day when your brain feels “fried”. Well, that's because it is fried. The stress hormone cortisol is released to keep you in a state of heightened alertness. It keeps your blood sugar and blood pressure up to help you escape from danger.
In the short-term it's meant to help you deal with life-threatening situations. Getting that document finished by the end of the day is hardly life-threatening, but unfortunately you can't tell your body that.
It's called the “fight or flight” mechanism and that's why exercise is so good at countering it. You don't need to imagine you're being chased by a sabre-toothed tiger (although it might help you run a bit faster); just the act of running will help reduce the cortisol in your body. Even a brisk stroll will have a similar beneficial effect.