The amount of exertion that a brisk walk gives you will vary hugely from person to person. This is a very important point in the article: >The Active 10 group

The amount of exertion that a brisk walk gives you will vary hugely from person to person. This is a very important point in the article: >The Active 10 group were also told that their aim was not to amble but to get their pace up so that they would be working their heart and lungs. Prof Copeland told them: "You are aiming to walk fast enough so that you can still talk but not sing." I think for a lot of people walking won't be enough to get to this state. In my experience you get a much bigger effect (especially on mood) if you make sure that you are getting to a point that you are almost gasping for air at least once or twice a day. Burpees, sprints, biking uphill hard, and rowing machine are good for this.