Lucy Mecklenburgh and Ryan Thomas argue if they go to the gym together.
The 27-year-old beauty is very happy in her relationship with the 34-year-old actor but admitted they've learned that working out together isn't a good idea.
She told Closer magazine: "Ryan is amazing - but we can't train together.
"We try to go to the gym, but we just end up falling out - we always argue at the gym.
"He doesn't like it when I tell him what to do.
"But he is amazing. He gives me lots of compliments and makes me feel beautiful - and I'm very complimentary to him too."
The fitness guru is keen to have a child with Ryan - who already has daughter Scarlet, 10, with ex-girlfriend Tina O'Brien - one day but she's worried about the impact pregnancy would have on her body.
She said: "I definitely want to be a mum one day, I've always wanted a family. It's definitely in my future but right now? I'm not sure.
"I'm 27 and busy with my businesses. It's in the future - but I don't think any time soon.
"There's definitely a worry about my body changing due to pregnancy too. Your body is never the same afterwards.
"And there's a hell of a lot of pressure on mums to snap back into shape.
"But your body does an incredible thing, so who cares if you've got a few stretch marks. You'll have an amazing baby.
"Ferne McCann and Binky Felstead look incredible after having their babies. They're definitely yummy mummies."
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