One of the biggest mistakes people can make happens when they are at the gym and they see someone lifting a lot more weight, or doing a more complicated exercise, and think that they are able to do the same. It's important to know what you can handle at the gym. The proper response is not to compare yourself to the gym-goer, but admire them and continue with your own preexisting workout.

Also, you can incorporate small steps with the goal in mind to eventually reach the other person's level. Attempting to do what the other person is doing immediately may result in a serious injury because you may not be at their same level.