The time when your child takes their first steps is magical and unforgettable.
But for one Norfolk mum it is particularly precious - as it has taken nine years.
Determined twins Thomas and Daniel have walked for the first time, despite mum Vicky being told by specialists that it would never happen.
Thomas and Daniel have a unknown neurological condition, discovered when they were 14 months old, which is has been suggested could be a form of spinal muscular atrophy.
The rare condition, which affects one in 11,000 babies, robs people of their physical strength by affecting the motor neurone cells in the spinal cord.
Mrs Bristow, 42, said: "When they were tiny and I was watching the other children learn to walk, children much littler than them, I was happy for the child that was learning, but it kind of broke my heart completely."
However years later, and following operations to straighten their legs, the Parkside School students have defied expectations and can now walk short distances alone thanks to a specialist gym for people living with disabilities.
The twins have been learning to box at the Able2B gym, run by consultant orthopaedic surgeon Rachael Hutchinson and retired British boxing champion and personal trainer Jon Thaxton.
And Ms Bristow, of Blofield Heath, said it was Mr Thaxton's can do attitude which turned things around.
She said: "One of the big differences with Rachael and Jon has been meeting two people that actually - unlike some of our experiences in the past - have the unfailing belief the boys can do it.
"I can remember Jon saying to me 'I'm going to get them walking, they can do it'. That's what he does and you know that he believes it completely and that gives you a lot more faith and trust in what he's doing.
"And then gradually you see the results. You see the boys going from they can stand up without their frame, they can take a few steps without their frame, to one day looking up while I was having a chat and they're literally walking around the room, together with their frame.
"Today they've had a bit of a set back because they've had a tumble but actually that's part of learning to walk as well."
And now, after years of not seeing her twins put their feet on the floor, she said: "What has happened now is like taking all that sadness, squashing it down, and then they're walking so it's like this massive burst of joy, it's just incredible."
She added: "It was just overwhelming."
Ms Bristow said when she took the pair boxing she just expected them to use their walking frames.
"But they took the frames away,," said Ms Bristow, who admitted she was a little apprehensive.
"They said 'trust us, we know what we're doing' and it was incredible.
"And Jon thinks they can walk, and that's really, really important because actually that's one of the first times someone has said that. One of the things is if you're told all the time you can't, then you won't."
The twins had also received support from their church where Ms Bristow said there was a "ripple of excitement" when they stood up to take part in the service for the first time.
"There's been an awful lot of happy tears," she said.
Mrs Hutchinson added: "It's not just about making their legs straight medically and dealing with that, it's about giving them the confidence and self belief and the self esteem.
"Nothing particularly special happened that day except they believed they could do it. So it's not just about getting them stronger and fitter.
Mrs Hutchinson said she was incredibly proud of the boys, who she had known for many years.
And that their progress epitomised what her and Mr Thaxton were trying to achieve at Able2B, where they tried to reverse the norm of those living with disabilities being told what they cannot do.
She said: "We can't say we can make everyone do something, but it's how much we feel like a successful person."
Able2B is running a Discover Your Ability event on June 2 in the ground of Norwich Cathedral, in partnership with the Norwich School and charity Just4Children.
To find out more about the event, Able2B, making a donation or sponship, visit www.able2b.co.uk
A mother's poem
Ms Bristow wrote a poem to her sons, it reads:
Grubby shoes
It had been laundry day
Ten minutes, now clothes away
Now the state I left, was fairly clean
When I return, slightly obscene
The boys had gone to get some air
And scattered mud everywhere
I think I turned slightly pale
To see the muddy footprint trail
The smears on the carpet, leaving clues
Of something that had once been chewed
And an odour drifting, not so sweet
Brought in by four little feet
I think for a while, then burst into grin
(swear I haven't touched the gin!)
Now let me explain to you
Why this mess, is a dream come true!
What I have in mind
Is how my boys got left behind
When other babies stood tall
Mine hardly moved at all
I thought catching up won't take long
But other babies were getting strong
Crawling, cruising taking steps
Hoping mine would be next
But the gap got very wide
Babies walking full of pride
It quietly broke my heart
They didn't seem to start
Professionals expressed a belief
I cannot express the depth of grief
I did not want it to be true
Walking was something they won't do
So, physio, boxing and an operation
Horse riding, parallel bars and patience
The mess I see fills me with elation!
Their triumph and determination
I never dreamed of this at all
My boys stronger, standing tall
Each muddy footprint brings me joys
My walking amazing little boys!
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