Low heart beat rates and sore knees.

After coming out of a nap or in a very relaxed state, my heart rate is 48 bpm, but most of the time my heart rate is closer to 60~67 bpm.  I understand people who exercise to the extreme - professional bicyclists - can get their rates down to sub-30.  But then again, their hearts are much larger as a result of all that training, and nothing good ever comes from going to extremes -- I just walk.

Once upon a time, I used to run, but after 30 minutes of running my knees would get extremely sore and I'd usually have to stop; I never got past 5 miles.  I figure sore knees was not the good kind of pain (unlike muscles being exercised) so I switched to walking, and then comes an enjoyment that you never get when running: peace and the time to observe and capture photos of events or things you pass by along the process of walking...like this picture of lonely berries.

A stronger heart = efficiency in moving blood and fewer heart beats.  I once knew someone who said that a person only has so many heartbeats in  their life, and once you use them up, you die.  There is no way to prove or disprove that, but it was really her way of excusing herself from doing exercises.