Henshaw, a silver and bronze medallist in swimming at the London and Rio Games respectively, had both legs amputated above the knee and had retired from the sport in 2017 to make the switch to paracanoeing.
The 33-year-old has been housebound and unable to train after the United Kingdom went into lockdown and said it was tough to come to terms with the Games being moved to July-August 2021.
"That was hard to get my head around, no matter how much warning you have. I felt a bit of a dip," she said on an International Canoe Federation podcast.
"I felt that lack of motivation, that 'why are we training because we have so much more time to stay fit for'. I think everybody knows, that last year before a Games, it steps up and you put your body through complete hell for that last 12 months.
"That's ok, because there's a light at the end of the tunnel. But then suddenly that light has moved even further away, and you have to think how are you going to get your body through another year of that?"
All canoeing events originally scheduled for May -- including the Paracanoe World Championships, canoe sprint Olympic qualifiers, and the ICF canoe sprint World Cup -- were cancelled after the coronavirus outbreak.
The opening two ICF canoe slalom World Cups, set for June in Italy and France, were also postponed and Australia's two-time Olympic medallist Jessica Fox believes there will be no more competition this year.
Fox, who won a sliver in London and a bronze in Rio, has been forced to undergo her canoe slalom training in the family pool due to lockdown measures in the country.
"For us we are not really sure if we will be able to attend, even if there are any events. Australia has said its borders will remain closed until September, possibly December," Fox said.
"I'm getting mentally ready not to compete this year, not to travel this year, and to try and make the most of the situation at home, and to put into perspective that this is bigger than us." (Reporting by Rohith Nair in Bengaluru Editing by Christian Radnedge)