Greg took a training session at the Eldon Square shopping centre as part of the launch event.
He won gold at London 2012 long jump and says now it's his turn to inspire others.
More top news
Predominantly dry over the coming few days with variable cloud & some sunshine. Cool start but daytime temperatures should recover a little
War veterans taking part in the walk of Britain got a singing send-off from school pupils in Northumberland.
A cast of the skull of St Bede - the English scholar who is considered to be the founder of English history - will go on display in Jarrow.