What Causes Discomfort In The Chest?

I have a problem of some discomfort/stress in chest whenever, I climb up in stairs or if I walk fast, especially when after my food and whenever, I have not had my full sleep. During such occasion, I just rest for a minute and then proceed. It becomes OK thereafter. This problem is faced, when I do not do exercise, for a few days. If I am regular in my routine walks, this problem slowly disappears. I am 46 yrs old. My Angio CT scan is perfectly OK, no blockages any where. My BP, sugar and cholesterol levels ar(clinical tests) are perfectly OK. I do not have any other problems and maintain a good health (height 176 cm and weight 80 kg) and pure vegetarian having clean food habits. My echo cardiogram, as per Cardiologist, shows some thickening of muscles of some portion of heart. He has advised my to take Aspirin for about 6 months and Concor tablet, as a preventive measure. I have a habit of keeping readymade tobacco in mouth in very small quantity at times. I do not smoke and no other drinking habits. I would like to know the reason, as to why it is happening and can I do some specific exercise to overcome this problem without taking any medicine? My parents and grandparents do not have any history of heart problem or any other recent day health issues like disbetes, BP or cholesterol. Kindly advice from your expert experience.