In the months leading up to 2015’s Fall marathons, RunWashington will follow several local runners as they prepare for their races. We’ll chart their progress as they train their legs, lungs and minds for the challenges they’ll race on race day. Each week, we’ll catch up with our runners and see how they’re doing. Matt Deters is an Arlingtonian who resumed running seriously a few years ago and has improved rapidly. Given his druthers, he’d already have retired from the marathon, but he’s giving it another shot.