Eric and all. Forgive me if I sound a abit negative or alrmist. We have recently lost a colleague and loved friend when he was jogging. He ALWAYS pushed himself to the limit. He jogged and bicycled for 10-15 miles DAILY regardless of the weather. He got a heart problem a few years back and almost died. He recovered but this time it was the real thing.

Sorry , but I wanted you to be careful.
Visit a doctor before you do anything extreme.