Push-ups are a great exercise! I only recently learned how to do them correctly where they don't hurt my wrists. Now I'm preparing myself for the air force's physical test. Don't forget about lower body exercises though.

I have never heard of anyone getting shorter with diet and exercise. I do know that everyone is their tallest in their 40s and most of us will lose up to 2 inches (gradually) by the time we hit 80.