From what RLR has written many times here - in my understanding - benign palpitations/extrabeats come from the vagus nerve, where they can "start up" due to many factors: "Anxiety" (maybe you should call it "long-time-overload-of-the-autonomic-nervous-system" because of stress or fear). And you don't have to feel fear of anything at the moment for this to happen, it's the long-time effect of being in a "nervous" or worried condition.
Many people have also reported that changing position can generate palpitations through the autonomic nervous system. And also "overload of the stomach" can cause pressure on your diaphragm (mellemgulv) which in some way is connected to the vagus nerve.
I would say:
1.Get your heart checked so (all) doctors say: There is nothing wrong with it. That means that your extrabeats not in any way are signs of anything dangerous.
2. Work with yourself in order to really BELIEVE that. (I know it's hard.) But really: Have they EVER continued and got you "sick "in any way? Or have they made you faint or die
? And then:
3: STOP thinking about reasons for palps, let them come and go - like irritating hiccups.
4: Have a lot of sex
if you feel like it ... (I have experienced that having sex can make you forget that you are having extrabeats ...)
Anyway: Best of luck from a guy who's almost gotten rid of extrabeats - maybe by following these 4 advices.