I've been having a sharp chest pain whenever I sneeze or cough really hard. Sometimes it flares up when I flex my chest muscle when working out too quickly. This has been going on for almost a year now. If I push hard on the spot where it hurts there is a slight pain.

It sounds like you may be experiencing costochondritis, which is inflammation of the cartilage where the ribs meet the breastbone. It's typically aggravated by coughing, sneezing, or sudden movements. While it's generally not serious, it would be good to consult with a doctor to rule out other causes and discuss ways to manage the discomfort.