They've seen every gym mistake in the book. Here's what personal trainers say you should stop doing immediately. Whether you’re a seasoned gym-goer or just getting started, there’s a good chance you’ve picked up a habit or two that’s working against you. Personal trainers spend their days watching people work out, which means they’ve seen it all and know what’s inadvisable. “As a certified personal trainer, there are several habits I consciously avoid both for my own well-being and also out of