Hi! I'm a 14-year old boy.

My mom keeps on telling me to exercise more. Currently, at best, I think I exercise for 1 hour once a week. I know i'm quite flabby, but I don't mind being so. She says eating junk food and sitting around all day isn't good for my heart. I don't see how my lifestyle is affecting my heart. When I put my hand on my chest I feel it beating strong and fast, isn't that ok already?