Decades ago, I moved to Boston after college with no employment, no apartment and no plan. I did, however, harbor an improbable ambition: to pedal passengers around the Public Garden lagoon in a swan boat. Is there a more perfect seasonal gig? Every spring and summer, these whimsically-shaped boats allow locals and visitors from afar to glide through the oldest public botanical garden in America. "It's been the same thing for 149 years," Phil Paget said, surveying a sunny afternoon on the lagoon.