Elle Macpherson changed her lifestyle after a "health scare" left her "very scared".

She said: "I had a health scare. In the end it was harmless, but I was very scared. Until then I hadn't understood how long trips, time shifts, stress, sleep loss and unbalanced nutrition could affect my health. I still thought I was living in the 1980s. My body sent me a signal and I changed the way I was living.

"As I got closer to 50 I realised that to stay healthy you need to do more than slap on the face cream. You need to combat the acidity in your body that causes many illnesses, balance the pH in your body and nourish its internal cells. A nutritionist designed an alkaline regime for me ... I slept more and drank more water and I added fruit and vegetables to my diet. Several weeks later I felt different."

Now she is in her 50s, Elle - who has children Flynn, 18, and Cy, 13, with ex-partner Arpad Busson and is now married to hotel heir Jeffrey Soffer - believes it is vital to work out and look after herself.

She told HELLO! magazine: "When you are 20, youth and beauty go hand in hand. At 50, your fitness is more linked to your personal wellbeing.

"You need to exercise 45-60 minutes every day. Any exercise is fine - walk the dog, take the children to school or walk home after work.

"My husband and I like skiing, waterskiing and paddleboarding. Without a doubt, the secret to longevity is exercising - but not obsessively."