More than 50,000 people have been pounding the streets in north east England, as they run 13 miles in the Great North Run.
The Red Arrows helped get everything started, flying over the start and leaving smoke in a very bright sky over Newcastle.
Most runners who take part do so to raise money for charity. They'll raise a huge amount of money for charity.
And who's this going well - Alan Shearer? Is the Newcastle United legend taking part this year?
And as for these guys, well they better moo-ve it if they want to reach the finish!