My husband told me at Cross-Fit they had him doing hundreds of pushups. I screamed, "Don't do it! I don't care if you lose the competition."
Why is this so scary?
Pushups works the pectoralis major and minor (chest) and anterior deltoids (front of shoulders). Doing excessive pushups (or any chest exercise) will strengthen those muscles to the point that they will overpower the back muscles - which are usually weak because we spend so much of our day slouching over a computer, leaning over cleaning, or holding a cute little one.
If you want to have good posture you need to strengthen your core with a balanced approach. A little bit of work on the chest is okay, but make sure you offset it with upper back exercises. Also, make sure to stretch your chest whenever you have a chance.
My favorite chest stretch - go to a corner or a door frame, place hands a little more than shoulder-width apart, lean forward until you feel the stretch in your chest, hold for thirty seconds.
Another key of good posture is strong abs and lower back. Make sure you hold your abs in tight throughout the day and whenever you get the chance press your tongue in the spot where the back of your upper teeth and the roof of your mouth meet. If you press hard enough it will straighten you up every time.
So remember - strengthen back, stretch chest, especially if you are a mom or have issues with posture already.
My favorite back exercise you can do anywhere - stand up straight, extend arms out to the side, level with shoulders, fingers pointing towards ceiling, contract upper back muscles, slowly bring arms in front of you while keeping back contracted, as soon as you lose the contraction go back to start position. Repeat three-four times a day.
Good posture will make you look ten pounds lighter and much more confident.