Push-ups

Although difficult to master, the push-up is an ideal exercise for increasing upper body strength.
Push-ups on your toes are extremely challenging if your like me and starting out with zero arm strength.  So why not begin with something more manageable and work up to doing a full push-up?
Start out with knee push-ups.  Once your fairly comfortable with these, begin the push-up on your toes and lower down keeping this same position.  Try to raise yourself back up while still on your toes.  You probably won't be able to accomplish this at first, but just the simple act of trying will bring progress.  Switch from the toes to your knees to complete the second half of the push-up.  Eventually you'll be able to do the entire push-up on your toes.