Push-ups are a great exercise that have tremendous benefits that include exercising multiple muscle groups and joints. Muscles that are strengthened include the chest muscles (pectoralis major), arm muscles (triceps), shoulder muscles (deltoids), stomach muscles (rectus abdominis and obliques) thigh muscles (quadriceps) and back muscles (erector spinae). What most people dont realize is that pushups are great for core muscles, including your abs, obliques and lower back. They are easier on your back than situps and effective not only in developing toned abs; but also to develop a strong back and can prevent back pain. In fact, situps can actually lead to back problems and many including the military have advised against situps.
What is that this is an exercise you can do anywhere, anytime and with no need for any special equipment. Pushups also burn more calories than many other exercises because they exercise muscle groups. You burn more calories doing a push-up than you doing crunches or bench presses.
If you want to burn even more calories ? Try burpees which add a squat jump to the push-up routine and add cardio benefits. You can vary them by spreading your arms further apart, elevating your feet, or holding positions longer.
The internet is loaded with pictures and testimonials of people who have taken the 100 pushup challenge.
Perhaps it is worth doing more but even this is a great start and can be accomplished by almost everyone.