Don't worry about other people, you are trying to lose weight for you, not them. I don't know why some people try to discourage others from being healthy and fit. Maybe it's an insecurity thing, I don't know.
I've had heart issues myself, well if you consider that I can quickly get my heart to 200+ bpm and issue.
I've actually gotten it to 236 bpm just for fun. It was funny to see the
look from my Cardiologist when he gave me a stress test... so I have trouble running too.
Once you reach the goal that think you want now, you may find yourself going passed it.