I have now been running for a couple of years I run out doors. I try to run about three days a week in the summer and try to run as much as i can in winter, but it sometimes drops to about once per week. My pace is very slow and I do it mainly to keep fit. I have though a place in the great north run in september which is a half marathon. I need therefore to build up to this standard. I run about 5-6 k but have previously built my distances up to 11-12 k. My question would be is strength training a necessity or can i do stuff like interval training and hill training, or should I keep to gradually improving my distance to a half marathon distance. My aim with the great north run is to finish it. It is my first time and i am very excited about it.