Push-ups are the best bodyweight exercise to do for your chest muscles, but after a few weeks of doing regular push-ups they become too easy. Thankfully, there are lots of great variations on the standard push-up: The Dive Bomber, the Star, and, my personal favorite, The Punch-Up. This is actually an exercise I learned in my martial arts class - one that the Sensei uses to punish us if we do something wrong or mouth off in class (unfortunately, that means I've done my fair share). It has turned out to be one of the best forms of push-ups, as it strengthens my knuckles and makes them more resistant for the many punches I throw. Added bonus: it's a great workout as well! The traditional push-up is almost all shoulders and triceps, but the punch-up focuses a lot on the forearms. You have to balance on your fists, so it's much harder to keep your body stable without your fingers splayed out wide. It is significantly harder than regular push-ups, so it's a good way to add variety to chest day.