Push-ups are quite possibly the best upper-body exercises. They build muscle, strength and endurance. Plus, they have the added bonus of not requiring any equipment other than your own body weight. To take advantage of all these amazing benefits, the LIVESTRONG webiste is hosing a month-long challenge. You'll build upper-body strength in just 30 days and you'll get the bragging rights of doing 60 push-ups in one day.