Over 30,000 people will join in the London Marathon tomorrow. Get set, says fitness guru Agneta Lindberg. Go back to the sofa, says Mel (& Sue) Giedroye

"If you are stronger physically then you will be stronger mentally, but whatever kind of physical activity you choose to do, be it gardening, taking your dog for a walk, going to the gym, aerobics - you have to enjoy it. I started training in an aerobics studio in 1983 and there was this fantastic instructor and she was the first training mentor I've ever had. I just looked up to her and thought `Wow'. What she was achieving in her training and her personal life and her business life was something to really look up to.

Exercise has so many positive effects. It enhances your self-confidence and self-awareness, and if you find a balance between leisure activities, resting, moving, sleeping and training then I think that is the ultimate aim. In Sweden, it is ingrained in our culture to go out skiing or skating from a very young age. But in England there isn't always a great deal of encouragement for young people. Even the diet that is provided in schools - in Sweden you would never find chips or Kit-Kats on the menu. Diet and exercise always go hand in hand. I can't create a miracle with a client who goes to McDonald's or eats pizza every night. I'm not a magician.

Ideally people should exercise three times a week, at least. Variety is the key, that's why the latest buzzword is cross-training. Cross-training basically means a little bit of everything - yoga, stretching, running - a good mixture. If you don't enjoy it, try something else. If you are on the treadmill and you think, `I hate this,' it won't be as effective as if you are thinking, `I am really getting somewhere here. I can feel my muscles becoming stronger.' If you have a positive attitude, you'll be more successful."

Agneta Lindberg, BA Hons, ACE Cert, is a personal fitness instructor based in London and writes a monthly exercise

column for `FHM' magazine