Thanks for your question on Healthcare Magic.
I can understand your concern.
In my opinion, we should definitely rule out heart and lung related diseases for your breathlessness on minimal exertion.
So
consult doctor and get done blood pressure monitoring, ecg, 2d echo and
stress test (trade mill test) to rule out heart diseases.
Get done PFT (Pulmonary Function Test) and chest
x ray for lung diseases.
If all these reports are normal then no need to worry for major heart and lung diseases.
Sometimes undiagnosed stress and
anxiety can also cause similar symptoms in young individuals.
So avoid stress and tension, be relax and calm.
Hope I have solved your query. I will be happy to help you further. Wish you good health. Thanks.