A first-time paraglider broke his back in two places after trying to fly in a machine he bought for £300 on eBay.
Roy Dixon did not take any lessons apart from looking at internet clips on YouTube, and made the mistake of tethering his paraglider to his car.
After less than a minute in the air, he fell 40ft (12.2m) and was taken from the scene near Hexham, Northumberland, by RAF helicopter to hospital.
Mr Dixon had been with his wife, Catherine and nephew, Michael.
Speaking from Newcastle General Hospital after the incident on Sunday, the 45-year-old volunteer for the Mercy Trucks charity, which delivers medical aid to the Third World, said he was embarrassed and had been "quite foolish".
He returned only a few weeks ago from disaster-stricken Haiti and said he had been looking forward to some fun after months of stress in some of the world's most deprived areas.
He said: "I should have joined a club and got lessons but I was trying to teach myself and learn from bits I had seen on YouTube."
Mr Dixon, who used to project manage golf course construction before working entirely voluntarily for the Christian charity, added: "The thing you should never do, which I did, was tether it to a solid object.
"I went shooting up in the air, then banged down on the ground. Then I went up again.
"As I was dropping, I was thinking, 'this is serious'.
"The pain was like an explosion going off inside me."
Mr Dixon, who has flown microlight aircraft in the past, broke two vertebrae which might now have to be fused.
But he said he felt lucky not to have been paralysed or killed.
"I am very blessed that I got off so lightly," he said.
"I am very embarrassed about the cost of the rescue and using all these resources up."