Michelle Salt knows all to well the value of the Canadian Blood Services (CBS), the agency that provides blood to patients across the country.

Salt, 29, who survived the loss of her right leg in a motorcycle accident in 2011, went on to become a Paralympian, and CBS hopes true stories like hers will remind people why their blood donations are so important.

CBS says the blood supply has dropped to its lowest level in five years. This weekend alone, it needs 1,700 Canadians to step up just to meet immediate needs.

"I spent seven days on life support, five months in hospital and in the end I ended up needing 28 units of blood, which is almost three times what my body holds," Salt recalled on Friday.

"Because I was given a second chance I decided I wanted to be a Paralympian. I made that happen in March when I competed in the first-ever snowboard cross in the Paralympics in Sochi, [Russia].

Michelle Salt

Michelle Salt lost her right leg in a motorcycle accident, but went on to become a Paralympian thanks to blood donors she never met. (Facebook)

 "If it wasn't for the 28 strangers who donated, I wouldn't be here today."

Canadians seem to have lost interest in donating blood. Even 20 per cent of people who make appointments to donate don't show up, the agency says.

The blood agency is hoping to find out from potential donors "is it lifestyle? Are there different activities that are pulling you away, that you haven't really thought about it?" Judy Jones of CBS told CBC News.

"Canadians are very generous in their support, so it is something that we're seeing as a trend that we're a little concerned about."

Melissa Tharp had never really thought about who was getting her blood donations. She's given 67 times in memory of her mother, who once got a lifesaving transfusion.

"To think this young woman [Salt] has this opportunity, then to go to Sochi and perform at such a high level in extreme sports. I can't even imagine getting on a snowboard myself, but I can give a pint of blood."