The best exercises to build the chest muscles are chest flies and chest presses done on the weight bench, and push ups – both basic and variations.  The best exercises for your abs include the various crunches – on the mat or on the exercise ball - that target the rectus abdominus (the ‘six-pack’) and exercises that target the entire torso, such as the bicycle, captain’s chair leg raises and the plank.  To build muscle anywhere in the body, exercise on 2 or 3 non-consecutive days each week.  Read about exercises for your chest and exercises for your abs from the Guide to Exercise at About.com.