Gift of Life held the Steps for Life 5K Run and Walk of Boston on Sunday, April 30. For two special people among the nearly 700 people arriving at the Chestnut Hill Reservoir, this was one of the most exciting days of their lives – they were about to meet for the first time, and one of them had saved the other’s life. How do you save someone you’ve never even met? You cure that stranger’s life-threatening cancer by sharing your peripheral blood stem cells or bone marrow.   After waiting for nearly two years since the transplant took place,…