Do about 50 jumping jacks, 25 push-ups, run in place for 2 minutes, and then put a mic to your chest. I GUARANTEE that you'll get the sound that you want lol. I did that **** in basic for 10 minutes straight and my heart was ready to explode out of my chest. If you have trouble I can get a Drill Sargeant to come to your house to get you going
De, also you can take a kick, and filter it and press it two times to make it sound like a heart beat that's what I did and it sounds amazing. I did that in the MPC.