In a Bogota clinic, 19-year-old Alberto Perez strains as he struggles to lift a weight with the two bandaged stumps of his legs. "For me, landmines are a terrible violence, because they hurt the innocent people."
Alberto wants to play basketball, but stands little chance of getting the adapted wheelchair.
More than 200 Colombians have been maimed this year by mines
CIREC, the main Colombian foundation providing rehabilitation, is entirely dependent on donations.
On the treadmill, Julio Cesar, aged 27, holds the rails and walks carefully to accustom the damaged muscles in his leg to the new prosthesis.
He has a wife and a child of 14 months. He used to be a farmer. "Now, I don't know what I will do to survive. I don't know how to go on. It's unfair - we farmers aren't guilty of this war."
They are two of more than 200 people maimed by landmines so far this year in Colombia. All of the irregular groups fighting the country's long and bitter civil war are increasingly resorting to using these so-called "silent soldiers".
No maps exist of where they are laid. Increasingly they are being put near schools and recreation areas - and sometimes even in the houses of people who have fled the fighting.
Last year the mines claimed a fresh victim every 17 hours.
The sleepy town of Corcorna, south of Medellin, is in the most landmined region in the whole of the country.
Most of the people here earn a living from the land. But it is a deadly occupation.
Carmen Julia Lopez walks stiffly across the main plaza in the shadow of the church, holding the hand of her seven-year-old daughter, Claudia.
Shards of the landmine which killed her husband last year are still embedded in her abdomen. Claudia has scars on her arms and her legs.
The three of them were walking along a path near their home when the mine exploded.
"We are very nervous now," she said. "Whenever I think of my dead husband, I can't stop crying. My daughter is very anxious because the mine scared her so much."
Up in the green mountains which tower over the town, Colombian Army patrols hunt the deadly mines, sweeping the jungle pathways with metal detectors.
Locating the home-made mines is no easy task
However, many of them can be put together at home for less than $1. Usually, they are made of plastic, and so are virtually undetectable.
Just in this area, five soldiers have been injured in the last two weeks. According to local Captain Hunter Cuartas, "With the way this war is going at the moment, the mines are the most deadly enemy we have."
There is a small note of optimism. Alvaro Jimenez, Director of the Colombian Campaign Against Landmines, has been in talks with the ELN, one of the rebel groups currently laying the mines.
"We are trying to create a zone where everyone can talk - the government, guerrillas, and communities, to try to intervene in areas which are affected to stop the mines being placed - such as roads and schools," he said.
The mines are small but powerful
However, even he admits that this progress is a tiny step forward.
General Mario Montoya, in charge of the most landmined area in the country, is pessimistic: "Day after day, the techniques they are using to lay these mines are getting more sophisticated... Every day they are affecting more and more the civilian population."
With an estimated 100,000 mines scattered throughout Colombia, this terrible violence will continue to affect the country for many years to come.