MassLive.comFitness a way of life for instructor, trainer Yesenia RiveraMassLive.comYesenia Rivera 1.jpg 9/9/2015 East Longmeadow, Yesenia Rivera leads a group exercise class at Century Fitness in East Longmeadow. (NEIL HAWLEY PHOTO)Elizabeth Roman | eroman@repub.com. "I was an introvert, I was shy so I didn't think I wanted to ...