RNZ National: 20th January 2018.

Exercise is even better than thinking for the health of your brain, says Harvard psychiatry professor John Ratey.

"Moving the body, moving the muscles, pushing yourself to do something more than you did before" boosts our capacity for focus and learning and lifts our mood - not unlike the effects of taking a little bit of Prozac and a little bit of Ritalin, he says.

Exercise boosts our levels of brain-derived neurotrophic factor (BDNF) – a substance Ratey calls "Miracle-Gro for the brain".

"We need to grow our brains if we're going to take in new information … The only way we learn anything is to have the brain grow."

BDNF is also a popular ingredient in mood-elevating drugs, and our mood is inseparable from our ability to pay attention, john says.

"When we're depressed we learn less well. It's harder for us to get into new territories and learn something new.

"There's no better way to raise BDNF than exercise… Your mood, your motivation is higher."

"When you exercise you are using more brain cells than in any other human condition… Doing a crossword or thinking about a problem you're using your brain cells but nearly as many as you would on your mountain bike or out swimming or walking. You're using many more brain cells – maybe not as intensely – but eventually you're using more brain cells than in any other human activity.

"Exercise is the top thing to do [for your brain]. All the hard-edge neuroscience people say number one is exercise, number two is socialisation, number three is getting enough sleep as well as having the right diet."

Listen to the Up This Way interview with John Ratey on RNZ National.