The Duchess of Cambridge is attending this major event for the first time ever

She'll be joined by Prince William and Prince Harry, too

For the first time as a member of the Royal Family, Kate Middleton will watch the London Marathon in public and will cheer on runners from the sidelines, along with Princes William and Prince Harry. Imagine being spurred on to run by actual royalty?

Together the three of them founded the Heads Together campaign and aren't afraid to address powerful mental health issues in public, ensuring we all keep conversations about mental health going. Heads Together is the Marathon's charity of the year, and the three hope that the event will be known as 'the mental health marathon'.

In the run-up to the marathon, the Duchess of Cambridge is reportedly hosting the Team Heads Together runners at Kensington Palace.

The royals have been doing their best to keep the runners motivated, too – in a video message to almost 40,000 runners who will take to the streets of London next Sunday, Prince Harry revealed that all participants will be given a special headband emblazoned with 'Heads Together' to wear during their 26.2 miles.

'You've been training for months, and the start line for the 2017 Virgin Money London Marathon is finally within sight' he said during the pep-talk. 'I'm sure it will be one of the most rewarding experiences of your life – William, Catherine and I will be there to cheer you all on.

'We're really excited that Heads Together is the chosen charity for this year's marathon – we want to use this moment to help end the stigma that stops people talking and change the conversation about mental health for good. You can make it the mental health marathon' he said.

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Kind of makes you want to start training for next year's, doesn't it?

The prince also talked about the importance of looking after our mental health and recognised many of the runners will have been affected by mental health issues.

'You can all play your part in the biggest ever movement for mental health' he added. 'Whatever cause you are running for, wear your vest with pride, and please wear your Heads Together headband too. Together we'll get the whole country talking about mental health.

'Good luck and see you at the finish line.'

We wish all of the 2017 London Marathon runners the very best of luck next weekend – let us know if you're running by tweeting us at @marieclaireuk.