I went in for an outpatient procedure yesterday. I walked 2 miles (at 5a) to get there because they won't let you drive home.
They put me on the heart monitor and before any drugs my resting heart rate was 51 - 55. It dropped to 48 once and any time
it hit 50 or below the alarm would go off. The nurse came over and shut it off.

I must be getting cardio somewhere.
I found this chart online. I'm not sure how accurate it is. I know some athletes have 40bpm.
Normal Resting Heart Rate for Men (bpm)
AGE | Athlete| Very Fit | Good | Above | Ave | Unfit | Poor
18-25 | 49-55 | 56-61 | 62-65 | 66-69 | 70-73 | 74-81 | 82+
26-35 | 49-54 | 55-61 | 62-65 | 66-70 | 71-74 | 75-81 | 82+
36-45 | 50-56 | 57-62 | 63-66 | 67-70 | 71-75 | 76-82 | 83+
46-55 | 50-57 | 58-63 | 64-67 | 68-71 | 72-76 | 77-83 | 84+
56-65 | 51-56 | 57-61 | 62-67 | 68-71 | 72-75 | 76-81 | 82+
65+up | 50-55 | 56-61 | 62-65 | 66-69 | 70-73 | 74-79 | 80+
Normal Resting Heart Rate for Women (bpm)
AGE | Athlete| Very Fit| Good | Above| Ave | Unfit | Poor
18-25 | 54-60 | 61-65 | 66-69 | 70-73 | 74-78 | 79-84 | 85+
26-35 | 54-59 | 60-64 | 65-68 | 69-72 | 73-76 | 77-82 | 83+
36-45 | 54-59 | 60-64 | 65-69 | 70-73 | 74-78 | 79-84 | 85+
46-55 | 54-60 | 61-65 | 66-69 | 70-73 | 74-77 | 78-83 | 84+
56-65 | 54-59 | 60-64 | 65-68 | 69-73 | 74-77 | 78-83 | 84+
65+up | 54-59 | 60-64 | 65-68 | 69-72 | 73-76 | 77-84 | 84+