The Biggest Loser trainer, 33, who has lost a huge 25kg since she gave birth to her first child, son Arnold, back in September 2017.
Hall posed with her mum, 61, in a matching swimsuit, showing off their hard-earned abs.
"Mum and I accidentally bought the same swimmers 😂👙," she fittingly captioned the photo.
"You’ve seen Mum in the TIFFXO workout videos smashing it previously 💪💪 She’s my #fitspo and has shown me the #happyfit way all my life 😍 She’s 61, a Nanna Ninja and so so fit (and happy!) 😊," she continued.
Before plugging her fitness program, "TIFFXO gets results at every age and stage of fitness ✌️️ tiffxo.com."
"Oh wow you are smoking @tiffhall_xo and that’s not your mum. I’m sure it’s your twin sister 😍," one wrote.
While another commented: "Woweee what amazing genes you have 👌."