They've got aches in muscles they didn't even know existed and they're all thoroughly exhausted.
But the hours they've been putting in at the gym are starting to pay off because Portsmouth's Biggest Losers are losing weight – fast.
Our eight News readers have just finished their second week taking part in the fitness challenge they're hoping will turn their lives around.
They've walked from Southsea's South Parade Pier to Eastney and back and used rowing machines to row around seven miles – further than the distance between Gunwharf Quays and the Isle of Wight.
Personal trainers Gary Lockwood and Jess Eacott are putting them through their paces and have been impressed by how hard everyone's worked.
And the weekly weigh-ins are making all those punishing exercise classes worthwhile.
At the end of the three-month challenge – run by Portsmouth's 24/7 Fitness – one of the contestants will be crowned Biggest Loser and walk away with a haul of prizes.
Top loser so far is Emma Hine who lost just over a stone in her first week of exercise and diet.
Her body mass index is coming down all the time and she's lost three inches from her waist. The 33-year-old mum, from Havant, has even dropped a dress size.
She's loving the whole experience and says: 'It's the best thing that's ever happened to me.
'The first week was really tough but I just had to listen to what Jess and Gary said to me and do what they said. I survived it and everybody is supportive of each other.'
The eight contestants – picked after finding out about it in The News and applying to take part – have been working out for two hours a day, five days a week.
Circuit training has been combined with spin classes and other routines designed to help them burn calories and tone up.
They've also been set a tough diet to follow and take part in fitness challenges every Sunday. 'The diet is hard work because it's boring,' adds Emma. 'But it's easy to do and it's cheap to follow, you just use things in your cupboards.
'It's things like jacket potato with tuna and chicken breast with vegetables and Weetabix for breakfast. I've been able to do it for the whole family which makes it easier.'
All eight contestants have lost some weight and some have seen their blood pressure lower and their energy increase.
'Everyone is continuing to turn up to the sessions despite the aches and pains of so much hard working out and Jess and I are really pleased with their progress,' adds Gary.
To keep up to date with their progress log on to 247fitness.co.uk