Paul Skidmore, who has 107 previous convictions which include armed robberies, got behind the counter at the One Stop Shop in Ocean Road, South Shields, and held the woman's arms to stop her pressing the panic button.
Newcastle Crown Court heard lone worker, who is in her 60s, had left the till area to tell the 38-year-old to put down some Shake and Vac he was trying to pocket from a shelf then returned behind the counter.
Prosecutor Emma Dowling told the court: "The area of the till has a door which restricts members of the public from going behind the till.
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"She had forgot to bold it shut.
"He, in her words, dived through the door and shouted he wanted the till.
"She tried to reach the panic button and he said 'you are not pressing any button' and grabbed both her arms."
The court heard Skidmore then used his back to pin the worker against the counter while he helped himself to bottles.
In a victim statement the worker said she was "scared and shaking" after the confrontation but refused to take any time off from the job she enjoys and was back at her post the next day.
The woman said she felt "physically sick" but determined to return to work, despite being offered time off by her bosses, as she feared she would feel "worse and worse" if she stayed away.
She said; "I love my job and didn't want to lose it.
"The staff from local restaurants pop in to check on me and support me."
Skidmore, of no fixed address, admitted robbery.
He also pleaded guilty to an attempted burglary at a Betfred shop in Stockton, Teeside, where he tried to jump over a counter.
Mr Recorder John Aitken sentenced him to two-and-a-half years behind bars.
The judge told him: "You have been told repeatedly, you cannot prey on small shops where there is vulnerable people.
"This has a terrible effect on people, she was a vulnerable lady who really enjoyed the social aspect of her job and seeing people then you come through the door and start pushing her around.
"You have to stop robbing shops, is the short message."
Paul Cleasby, defending, said Skidmore was "at pains not to hurt anybody physically" but added: "He, perhaps, does not realise how distressing it is to the shop workers trying to earn an honest living."
Mr Cleasby said Skidmore has completed courses in custody and is trying to combat his addictions.