At my house we have a saying, "Not trying is as bad as lying." It was created in response to hearing my girls say, "I can't do that" before even making an attempt. Today, my Equinox trainer Hannah busted me saying the exact same thing.
Hannah told me to jump up and catch a high bar on the cable pulley machine for hanging knee lifts. I said, "I can't do that." She shook her head; she wasn't buying my negative attitude and had me try until I caught the bar. When I jumped and finally grabbed the bar I felt like the strongest woman in the world.
To learn my other gym gaffe keep on reading.
One element of the last strength training circuit was timed push-ups for a minute, by the third round my arms were noodles. I put my knees on the ground and asked if I could do "women's push-ups." Her response was a clear, "No." She followed with, "Those are not women's push-ups." My bad. Those are knee push-ups, which are done to build strength for push-ups in a plank position. Language makes a difference. Lesson learned.