Mat, a former Gloucester and Bristol Academy player, and his wife Lucy were expecting twins when, tragically, one passed away in the womb.
The couple are now proud parents to baby daughter Freja, and have their hands full as any new parents do, but have also found time to launch the Foundation.
The Capella Foundation is dedicated to raising money for research into medical complications during pregnancy, and supporting families suffering such trauma.
So, Mat and Koree plus five friends, 'the Capella Wolfpack', will spend 40 minutes every hour on a different fitness exercise, starting at midday tomorrow and ending on Sunday lunchtime. All the money raised will go to Bristol-based charity The Mother and Baby Trust.
Koree explained that, as someone who is expecting a baby with partner Emma this summer, he's doing anything he can to help.
"Obviously it would have depended on whether we were still involved in the Premiership.
"It would have been great, of course, to be at Twickenham with Gloucester, but I am delighted to be able to help with what's clearly an immense challenge.
"My partner Emma and I are having a baby as well. So for any families that have troubles during pregnancy, this is ideal to help support them through it.
"These sorts of issues don't tend to be talked about a great deal. So raising awareness of problems or complications and lending support to people who are experiencing difficulties, I think that's pretty important.
"It's certainly not the easiest of situations to be going in for your regular check-ups and to be told there's a problem, that's always going to create worries.
"Unfortunately one of the twins passed away, and that's extremely sad. But to have an opportunity to do something like this, it's a real honour, for me and for the family as well."
Anyone can sign up to join in the specific exercises, ranging from swimming and Zumba to the bleep test.
The majority of the challenges are taking place at Westbury-on-Trym's David Lloyd gym, and Britton has been amazed at the support so far.
"We've already had a donation of £1,000 from America, from a turfing company: £1,000, that's amazing. So I think that pushes the total up to £6,500 so far.
"Any support anyone could lend would be massive. They can sign up to take part in any of the fitness challenges and we'll have a barbecue with a band playing at the end.
"It's going to be some event!"
For more information about the fitness challenge or to sign up for exercises, log on to www.thecapellafoundation.com.