Walking is something many of us take for granted, but it has a number of physical and mental health benefits.

Shane O'Mara is Professor of Experimental Brain Research at Trinity College Dublin. He has written a book, In Praise of Walking, all about the science of how we walk and why it's good for us.

Shane says that the moment we first learn to walk "signals a really important change in development".

"We're designed by evolution to engage in moderate levels of walking right throughout the course of the day, right throughout the course of our lives."

"We can easily walk 10 km a day almost for indefinite periods of time, and it confers enormous benefits on us physically and mentally."

These physical benefits include better digestion and increased strength in our legs and heart. Walking is also good for mental health issues such as depression, and may even help decrease the risk of dementia.

Shane says: "Our modern world is not designed to facilitate movement, but people underestimate how good a walk will make them feel."

He joined us on The Last Word to explain more about the joys of walking.

Listen to the interview in full by pressing the play button on this page.