No one is perfect, and no successful athlete has ever gotten to his or her elite level without a few bumps along the way. The one thing that puts seasoned trainers and gym-goers under the same denominator with beginners is mistakes. Everybody makes them; and some are more common than others, no matter how many years of experience you have. Even the professionals can make errors when trying to build muscle and strength,” Jeff Yellin DPT,CSCS, USA-W, ART, Partner and Regional Clinical Director at Professional Physical Therapy, says. “The key to success in the gym is variability and consistency.” Mistakes are part of a learning curve.