For two-and-a-half million years or so, humans were hunter-gatherers, on their feet for an average of eight hours a day. It's only for the last 100 years or so that people have been spending eight hours or more a day sitting down. Physical exercise and activity are a necessary counterweight to overstimulation by too much information, stress at work and the hectic pace of life. Movement and activity are fun, and they have been shown to underpin mental equilibrium.

What's your situation?

• Does your daily schedule include regular slots for exercise?
• What sort of exercise do you enjoy? Swimming, rambling, running, dancing, cycling?
• Have you done a full 30 minutes' exercise today?

A few suggestions:

• Get off the tram one stop early. Take the stairs, not the lift.
• Take a stroll, or walk your neighbour's dog.
• Arrange to play football or boules with friends.
• Stand up at least once an hour at work. Stand up to make phone calls.
• Do whatever you enjoy, but do it regularly – ideally three times a week for 30 minutes each.