I get so fast heart rate after minimal cardio exercising that i have to stop. can you please tell me how to overcome this problem?

See doctor: You should have a full check up to see what is going on. It may be related to your thyroid, your diet, your heart, etc. Either way, it needs to be evaluated by a physician.

Fitness evaluation: If you have symptoms with exercise that you think are abnormal, you should see your doctor to make sure you are otherwise healthy (not anemic, no evidence of systemic disease, etc.) then, if that is all normal, consider having a fitness evaluation that includes an exercise test to see what your response is to incremental exercise. A common cause is simply being out of shape.