I plan on doubling whenever I can. I am just in base-building mode right now. What is the shortest distance (or time) or time for a double that will give you benefit (other than getting your blood flowing and loosening you up)...Would it be 2 miles? 20 minutes? Or is there a benefit to doing any amount of distance as a double? My plan isn't necessarily to run this distance, I just was curious if running for 15 minutes right when I woke up did any good other than to loosen and wake me up in the morning