Generations of joggers, walkers and runners gathered at Washington Park in Oak Bluffs on Saturday morning for the 22nd annual Sullivan 5K Run and Walk for Health and Fitness. The fundraiser for the Martha’s Vineyard Hospital had all the trappings of a family reunion and social until the race began and the group suddenly rushed en masse down the street. Prior to the start, participants lingered about, sharing stories and sipping from bottles of water.