The reason for contracted chest muscles is probably improper posture. Do you sit a lot or work on a computer? This is easily prevented. Just do a few sets of pushups and a few rounds of stretching throughout the day.

Stress is something you have to get under control yourself. Learn to take it easy. Refuse to be bullied at work and stand your ground when you have to.

One thing you can do to minimize stress is physical exercise. Get off the computer and do something about it right away. Head to the gym, start running or cycling in the morning, whatever works best for you. But make sure you push yourself HARD. An intense 60-min. workout 3x per week will greatly improve your conditioning and clear up your mind before you know it.