If your mind's constantly wandering, try these tips from Harriet Griffey, author of 'The Art Of Concentration' (Rodale, £9.99), to help you focus.

If you grab an espresso to help you get going on a task, you could be making things worse. While coffee can briefly make you feel more alert, it's a short-term fix. Caffeine also stops the body's naturally calming agents doing their job, so you may find you end up less able to concentrate for longer.

Once in the bloodstream, caffeine attaches itself to nerve cells, which fi re up in readiness for an emergency, but also stops a calming and naturally occurring substance, adenosine, from attaching to those same nerve cells. Adenosine actually damps down nervous activity so, in the long-term, the negative side effects outweigh the benefits.

What you eat can make all the difference to your concentration. It's not just a grumbling stomach that can distract you - a low or seesawing blood-sugar level affects both your energy and your ability to concentrate. The brain's primary source of energy is glucose, and it likes a well-regulated supply, rather than peaks and troughs that can occur when there are long intervals between eating. Foods with a low GI or glycaemic index (the rate at which carbohydrates are converted into glucose for use in the body), such as oats, whole grains and baked beans, which release more consistent levels of glucose slowly over a sustained period, are best.

A simple way to notice when your concentration has wandered is to say ‘Stop!' to yourself. Rather than consciously trying not to think about anything else, focus on the task in hand, and whenever a stray thought encroaches on it, say ‘Stop!' This will bring your attention back. You'll have to do this over and over again at first, but keep at it and you'll find yourself saying ‘Stop!' less and less. You could also wear a rubber band around your wrist and ping it when you sense your thoughts beginning to distract you. The sharp ping instantly stops the thought and focuses your mind.

Modern life can takes its toll, particularly if you live in a town or city. Constantly having to monitor our surroundings by avoiding other pedestrians, looking in shop windows and trying to cross roads safely comes at a price. Although stimulating in short bursts, it consumes much of the brain's processing power to stay alert. Take some time out from the urban environment - like having lunch in a park - to help restore your attention.

Be consciously aware of a time when you really did concentrate. Perhaps you were listening to a piece of music, talking to a friend, or doing a crossword. What did that feel like? Anchor that experience in your mind and make the memory as real as you can, so you can visualise the same sensation at a later date. This is the feeling you are aiming for when you truly concentrate: a sense of being very clearly in the moment.