[header] How to get bigger chest muscles (pecs ) [title] Do push ups. [step] This often-neglected exercise focuses on building up your shoulder and upper chest muscles. Lie face-down on the floor and start with your hands about shoulder-width apart, with your legs stretched behind you. 
Push your body up from the floor with your hands until your elbows are straight, then lower yourself until your arms reach a 90 degree bend. [substeps] Do 3 sets of 15 push-ups, or as many as you can before growing fatigued.