Since you are 35 with a strong family history of heart disease , you must get a fitness evaluation done before embarking upon an exercise programme. Even though you are not an active smoker, both your parents used to smoke regularly which has an impact on your health too as you must have been exposed to the smoke as a passive smoker. Also if either of your parents smoked at the time when your mother was pregnant with you, it must have had an adverse impact on your heart and blood circulation too! Even though your weight is normal, you must avoid intense forms of exercise like jogging, running or skipping etc. If your body is not used to much activity or if you have been sedentary till now, you should begin with low intensity exercises and for shorter durations, say 15 minutes of walk at a normal pace. Always warm up by walking slowly for 5 minutes in the beginning and walk for 5 minutes at a normal pace and then again walk for 5 minutes slowly to cool down. A warm up before and cool down after exercise helps to raise the pulse slowly and brings it down slowly without causing any casualty. Walking is the safest form of exercise to begin with. If you experience any chest pain, or physical discomfort even after walking for 15 minutes, then you must consult a cardiologist.