When's the last time you donated blood? Giving blood is one of the simplest ways for any of us to save a life, and right now Canadian Blood Services needs our help more than ever. Canada's blood supply has been labelled "critically low" and is at the lowest level it has been in years. In fact, current stores would run out in three days without replenishing. Yet Canadians who are ill or experiencing emergencies need blood every day. The blood that is donated by average Canadians is essential to saving the lives of people undergoing cancer treatments and heart surgeries, and  those who suffer life-threatening injuries, because of traumas like automobile accidents. According to Canadian Blood Services, more than 50 percent of Canadians report that they or their loved ones have needed blood or blood products for medical care in the past. If you've never thought of donating, there's no time like the present. Read up on eligibility requirements from Canadian Blood Services and book your appointment today. This could be your best chance to save someone's life. Learn other ways to give someone the gift of health. (Photography: Thinkstock)