<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hi. I was diagnosed with heart failure a few months ago. After an MRI on my heart I was informed two weeks ago that the mild heart failure had completely reversed. However, I am still on the lowest dose of beta blocker and another one that helps strengthen my heart. I was told that I can exercise strenuously ie speedwork etc but to build up slowly which i have been doing. My problem is that I still feel really rough. I went for a gentle 30 minute run yesterday which was fine, but I have woken up today with pain in my chest in the centre and radiating out across both sides and a feeling that I am not getting enough oxygen when I breathe. I have been training for about three weeks with this problem happening for the fourth time now. If i am better why do I feel so rough?My diet is excellent, my knowledge of how to train is learnt from a Navy seal so its not that Im overdoing things.  <response>: Respected user, HiT hanks for using Chat Doctor.come have evaluated your query thoroughly. This is in relation with decrease ventricular compliance to cope up with the fast requirement of needed quota of fresh oxygen to the lungs. It is not that you are overdoing the things. Hope to clarify your query Welcome for further assistance Thanks for using Chat Doctor .com giving opportunity to assistWishing fine recovery Regards dear take care 