There are gyms that offer only spinning classes. “They are a great workout and very effective, too,” Romero says. Going to a class is a good idea for a lunch break activity. Exerting a vigorous effort on a spin bike for 10 minutes will burn about 100 calories. To get the biggest burn, though, keep the intensity high for as much of those 10 minutes as possible. If you can’t maintain a fast pace, opt for an interval workout that alternates between bouts of sprinting and recovery.