39 yr old male friend in a new high stress job working 100 hrs/week. 2 episodes of chest pains this week and shortness of breath lasting 15-20 mins.?

Anxiety or ??? He should go directly to his doctor. This could be just due to anxiety and stress, but it also could be a heart attack. These symptoms should not be ignored. He is awfully young to have a heart condition, but he would not be the first 39 year old to have a heart attack.
Get checked! Even though it may be that the chest pain is musculo-skeletal in nature at 39-yrs of age and continuous stress the possibility of myocardial ischemia is very real and potentially devastating so my recommendation would be to be seen by a cardiologist asap or even an emergency room for at least an ECG and blood work.