I've hit the magical 30 minute mark a few times, and am wondering what the best way is to improve (I am quite a long way from 5k after 30 mins). I am thinking of mixing up some runs of the "see how far I can get" variety with some more interval-type runs - slow jog with faster sections, or fast walk with faster sections. But is it better to work on speed or distance, or both? Should I be trying to go faster (covering more distance in 30 mins) or further (getting up to 5k, regardless of how long it takes)? Is there a best option? Will I end up doing both anyway?