I'm 42 years old and before heart attack was in very good shape. In fact, a month before my heart attack, I was in the middle of a move and hauling boxes up and down the stairs of my apartment probably 20 to 30 times a day and never even blinked. However, now, 10 days after my attack, I go up 1 flight of stairs and I am winded and have to catch my breath. Is this normal? And how long will it last?