Time and time again I have had women tell me that they "can't" do a pushup. My answer is always the same, "Yes you can! You just have to build up to it!"
The biggest issue I come across is poor form. As you build your strength it is not a problem to start out on your knees. 10 pushups from your knees are doing more for you than 10 pushups with poor form. However, the goal is to start working your way to doing pushups from your toes. If you can even do 1-2 pushups from your toes and the rest from your knees that is fine!
Why do pushups? It is one of the best and most dynamic core exercises out there (think about it, you just made plank even harder, and the whole world has been raving about the benefits of plank pose!) It simultaneously works your chest, shoulders and triceps. Depending on the variation you can also activate different back muscles, and your glutes (pictures below).
1. Keep your hands in the same plane as your shoulders. They can be out to the side, or directly below your shoulders depending on the variation, but they shouldn't be above your shoulders.
2. Your back should be straight. Your butt should not lift or drop.
3. Your head should be in the same plane as your body.
4. Lift and lower yourself as far as possible. I ussually go down until my chest or nose touch the ground depending on the variation.
5. Keep a nice even pace. Move slowly if you can. It's more challenging!
6. The only thing that should be moving is your elbows!
Pushups can be done anywhere, and mixed up to keep them interesting. You will really reap the benefits of doing this exercise correctly!
The picture below is 1 leg pushups. This really activates your glutes, and works your core and upper body a bit differently. If you want to try a harder variation this is one of my favorites. Note that my form stays the same. Only my arms are moving, and I lower until my chest touches the ground before returning to the starting position.