In reply to Franco Cookson: In order to get it lower you need to understand how you have got it so low in the first place. I think divers have the capacity to get the lowest heart rates so that'd be a good route to ivestigate.
From what I knnow (which may be rubbish but it was in a cycle training book years ago) the pulse is obviously liked into your heart beat. So your heart needs to pump blood around your body and each beat is a pump of blood. The larger you can make your heart cavity the more blood it will pump and the less beats required. To get a larger heart you need to do endurance activities such as all day in the mountains or cycling.
Secondly you want the heart muscle to be strong so each pump can move all the blood. A strong heart muscle comes from doing anaerobic activities pushing your heart rate as high as it will go for as long as possible. Cycling is great for this.
Anyhow, your pulse is already great and you're lucky enough to have a lot of time on your hands. Don't waste it in the pursuit of this nonsense.