Oneonta Man crosses the finish line in Boston Marathon Thomas Slicer hasn’t been a marathon runner all of his life. “I only started training for marathons last year,” he said. “Before that I was training for all of the shorter distance races.” Mr. Slicer turns 28 in June, and he just finished his first Boston Marathon in April — the average age for male runners in that 26.2-mile run is 42. It’s the world’s oldest annual marathon and ranks as one of the world’s best-known road racing events. “There are so many inspiring stories that come out of the Boston…