The father of missing chef Claudia Lawrence, who vanished in March 2009, said the recent discovery of three women who went missing 10 years ago in the US has given him hope that his daughter will be found.
Speaking at a race organised by charity Missing People, Peter Lawrence said he hoped it would not take as long to find out what had happened to her.
He was attending the Miles for Missing People's 10km run on Clapham Common, south London, which was started by Kate McCann, whose daughter Madeleine disappeared on holiday in Praia da Luz in Portugal's Algarve in 2007.
Lawrence said of the event: "It means a lot for the charity, which means a lot for me. It's good for raising the profile, I'm walking around with a poster with Claudia's picture on it.
"We've got to keep the profile in the media, because someone obviously knows what's happened to Claudia and one day we're going to find out. I just hope that it doesn't take too long though.
"It's good to meet up with other people in the same position as you. Kate and I gave each other a big hug earlier this morning."
Lawrence, who did not take part in the run himself but "handed out medals at the end and offered general support", said he had been heartened by the recent discovery of Amanda Berry, Gina DeJesus and Michelle Knight in Ohio, a decade after they went missing in separate incidents.
"It does give you hope," he said.
"I just hope it doesn't take that long. It's difficult, some days are worse than others but we've got to keep going for Claudia's sake."
Around 500 runners took part in this year's race, which aims to raise funds for the charity's 24-hour helpline.
Lawrence said the helpline was "extremely important" by offering support to families of missing people across the UK.
More than four years have gone by since Miss Lawrence was last seen near her home in Heworth, York, on March 18, 2009.
She was reported missing after she failed to arrive for her 6am shift at the University of York the next day.
North Yorkshire Police launched a huge inquiry which has subsequently been scaled back.
Detectives have repeatedly said they believe Miss Lawrence was murdered, with her solicitor father leading a relentless campaign to find out what happened to her.
Others attending the race included Rachel Elias, the sister of missing Manic Street Preachers guitarist Richey Edwards who disappeared in 1995.