We all want to make the most of our workout time and prevent injury, so we asked Jillian Michaels, author of the upcoming The 6 Keys: Unlock Your Genetic Potential For Ageless Strength, Health, and Beauty [1], the biggest mistake people make in the gym. "Hideous form," she told POPSUGAR at an event for AquaHydrate [2] to celebrate the launch of their partnership with the Breast Cancer Research Foundation (BCRF). "One: that's totally ineffective. Two: you're probably going to get hurt." To develop proper form, Jillian suggests hiring a personal trainer for a session to take you through the exercise. If a one-on-one session isn't possible, looking to the internet can be an easy way to check the correct form prior to trying an exercise. POPSUGAR Fitness is a great resource when learning proper form, like these standing core exercises [3] or fun moves with the pulley machine [4].

Since beginners are most likely to make this mistake on form, Jillian recommends starting with her beginner's program [5] "so you can build solid foundation, get results, and not feel intimidated. You want to take action, but action that is misinformed is going to do a lot of damage." Master your form before moving on to more complicated exercises and heavier weights. Your goal is to stay consistent and injury-free so you can keep working out.