Running

Ok next year I wan to do 5k below 20 min. My plan is to simply start with 1k sub 4 min and then just make extend the distance but by bit until I reach my goal. Does that approach sound good. Will mix it with some different runs and intervals.

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Best way to improve as a runner is to be consistent about running. Your approach sounds fine but my worry would be burning out because that’s a hard effort quite often. 

Even running 5 days a week for a few months without any effort at all might get you to sub 20 depending on how close you are now.

All about consistency!