"Push ups should be a staple in everyone's training," writes Lee Boyce in this month's Men's Journal. "This bodyweight movement creates a safer environment for your shoulders than lifting barbells—especially if you've got muscle imbalances—and they work the core better than most bench press variations." And what's more, they're simple and can conveniently be performed anywhere. The story goes on to explain the best standard push-up form and then offers ten innovative ways to spice things up and get more from the classic exercise.