Water

Drink lots of water. Try to consume at least 1.5 - 2 litres a day. Always have a bottle of water on your desk at work, and sip regularly during the day. Put a bottle on the kitchen table and sip whenever you walk past. Being properly hydrated will improve your running and your complexion! Tea and coffee don’t help: they are diuretic (i.e. they make you urinate more) so they increase the need to drink water. (Herbal or fruit tea is OK.)

Track your food and your miles

Keep a food diary. You might be surprised by what you are really eating, even if you think you have a healthy diet. For a week, keep track of everything you eat, and break it down into carbohydrate, fat and protein.