When you're obsessive, like me, searching for something unattainable can become unhealthy... it's like falling through the air and grabbing at the clouds.

To say I have played through four World Cups, two Lions tours, 91 international games and a ridiculous number of injuries and other setbacks gives me an incredibly special feeling of fulfilment. I know myself well enough to know that I will never truly be satisfied.

I play with a fear of letting people down. That's what motivates me.

I like to think I play rugby as it should be played - there are no yellow or red cards in my collection - but I cannot say I'm an angel.

Playing the game, representing the team, giving my all and never letting go has meant everything to me.

To make this announcement fills me with great sadness, but I know I have been blessed in so many ways to have experienced what I have with the England rugby team.