Why does the heart flutter at rest only?

Flutter: I read your question as "i only feel my heart flutter at rest". There are many causes of what you may be feeling, but most likely these are benign "skipped beats" most people have them, some people feel them and then only at certain times. Classic is rest, coming home after a busy day and sitting down, or lying down in bed. Discuss with your doctor :-).

Two reasons.: When you are up and active the heart is beating more rapidly and there is less time between beats for funny events to occur. Secondarily there is less awareness and more distraction when you are up and moving.