When Jeremiah Thompson toes the start line of the Athens Marathon today, he’ll do so with his grandfather on his mind.The 36-year-old Vancouver man and his longtime friend, 31-year-old Dimitry Makhanov, flew more than 6,000 miles to run the original marathon — a 26.2-mile trek from the city of Marathon to Panathenaic Stadium in Athens, Greece. This will be the first marathon for Thompson, who is dedicating the run to his grandfather Dewey E. Clark, who died last year at age 89.“This is going to be the defining moment of paying homage to my grandfather,” Thompson said.Three years ago, while on his honeymoon, Thompson saw the finish of the Athens Marathon. He had never heard so much cheering as he did when runners, dressed as warriors wearing breast plates and carrying shields, ran into Olympic Stadium toward the finish line. They were reliving history, following the course a foot soldier from ancient Athens took to deliver news of the Greeks’ victory over the Persians during the Battle of Marathon in 490 B.C.“That was just awe-inspiring,” Thompson said.Thompson had never been a runner — he preferred mountaineering — but after his grandfather died in July 2015, Thompson felt for the first time a desire to take up the sport his grandfather loved.Thompson’s grandpa ran his first marathon, the Tri-Cities Marathon, in 1980. In 1992, however, a prostate cancer diagnosis meant he had to give up his marathoning. Clark beat the cancer but was never able to run another marathon. He did, however, continue to run shorter 5K and 10K races until about 2000.The years of conditioning meant that after being diagnosed with congestive heart failure in 2009, Clark’s heart, though weakened, kept pumping and his lungs never filled with fluid, Thompson said.