You won’t be bored on the treadmill here. Marathoner Becca Skudder opened Boston’s first running studio to blow the dust off uninspiring indoor runs. In her North End spot, power walkers stride alongside marathoners for sprints, intervals, long distances and hills during three classes, including a heart-pumping strength and training combo. Training for your own 26.2? There’s a class for that. Bonus: MyStryde’s Woodway treadmills don’t have the distracting thump of gym machines.