I have been trying to combat my anxiety (mainly heath related) with exercise.
Today I ran for 12 mins and 5 mins out of a 45 min walk. A message flashed up on the treadmill screen saying my heart rate was 178. I felt a bit puffed but nothing special, I'm not very fit so this was me running at my max but didn't feel sick or anything.
I've now googled max heart rate for my age and really scared I have damaged my heart and will have a heart attack 
I don't have palpitations now, but sometimes do get them with an anxiety attack, if I start to get them how will I know if that is a heart attack brought on by exercising or just my anxiety?