I'm not one to blow my own trumpet - but you may have noticed that I'm becoming a bit of a fan of extreme sports!  Recent charity efforts have really seen me test myself to the limits both physically and mentally - which is why I'm urging all your readers to sign up for a truly inspiring event, raising money for a charity very close to my heart. 

But you don't have to cross the channel or swim through shark-infested waters to help make a difference.  In fact the charity Cardiac Risk in the Young (CRY) is inviting people from across the UK to join them in their annual Heart of London Bridges Walk, which takes place on July 20. 

The walk will take you over eight of London's bridges - a course of about 8km.  As well as helping to raise much-needed funds for this special charity - of which I am proud to be a patron - it also signifies the eight young people who tragically die of sudden cardiac death every week in the UK. 

This condition - which goes undiagnosed and usually affects apparently fit and healthy adults aged 35 and under - has a devastating impact on families.  Yet in many cases, with early screening and greater awareness, these deaths could be prevented. 

That's why we need your support on the 20th.  To find out more or to sign up for the walk, please log on to www.c-r-y.org.uk or call 01737 363 222. 

David Walliams,

Comedian, actor and CRY patron