He received an incredible update on Wednesday, as he was told the mind-blowing total he's raised so far for Children in Need's ULTRA Ultramarathon Challenge, which you can see in the video below…
The star had previously said he wouldn't cry until the finish on Friday but he couldn't hold back his tears after hearing one listener's message.
Barbara, who had previously contacted the show by post, called in to leave a heartfelt message of support. She said: "Hello, Vernon. It's Barbara. Now I just wanted to send you lots and lots of encouragement on running your ULTRA Ultramarathon, wow! But I know you can do it.
"Now if it gets tough, just think of all the smiling faces of the children you're helping. I'm so proud of you. Now I wish I could be there to cheer you on, but I shall be there in spirit. So just lift up those feet and keep going. And I'm sending you lots of hugs, take care."
The emotional presenter said to his stand-in on the show, Richie Anderson: "That’s Barbara who wrote me a letter after I’d been on air for a month.
"And she said thank you for bringing an old lady into the light. And it's had a massive effect on me that letter. It's probably one of the most heartfelt letters anyone could ever write… Oh that's done me that. I didn't want to cry until Friday!"
Vernon then said: "We've got so many special people associated with this show. And Barbara, I think, Barbara represents so many people in Great Britain who feel like they're, you know, either homebound or just a little bit trapped. But when she wrote that letter - all we do on the radio is just talk and we try and relate to people and, oh man, you've done me there, proper done me."
Vernon finished by saying: "But yeah. God bless you Barbara, thank you very much for your message, it means a lot." The presenter has embarked on a challenge for the yearly fundraising event that will see him take on a 100-mile trek over the course of four days.
His wife Tess wrote on social media on Tuesday: "Wishing @vernonkay all the luck today as he embarks on his epic 4 day 100 mile ULTRA ULTRA MARATHON in support of @bbcin Children in Need. Such an amazing cause and we'll be supporting you every step (and there's a LOT of them!) of the way."
Giving listeners an update on Wednesday, Vernon said: "I did promise myself that I would walk 40 [minutes], run 40 [minutes], walk 40, run 40 minutes but, I’m not just saying this, and it sounds really soppy, but the fact that people are taking time out of their busy schedules to come and stand by the road and whoop and holler and cheer and put money in the buckets…
"I walked for 20 minutes and I've run the last 12 miles because it's so inspiring!"
To stay up-to-date with Vernon's progress, listen to his regular updates into Radio 2 shows across the week and listen back on BBC Sounds. To make a donation, go to https://donate.bbcchildreninneed.co.uk/R2VernonChallenge