The best way to motivate yourself to push through that extra rep is by having other people by your side to cheer you on. Plus, it’s hard not to get inspired by your classmates.
In a group exercise class, you don’t have to worry about being better than everyone around you. Everyone was a beginner at some point. There will always be someone stronger than you in class. Let that motivate you, not intimidate you! When you see someone next to you lifting heavier or moving faster, it will inspire you to push your limits.