I have been running since the start of the year and have completed a couple of 10k races and am now training for the Great North. I have started doing the majority of my running on grass and can really recommend it. It is much easier on the joints (important for me since I am 6 foot and 13.5 stone!) and really builds leg strength compared to concrete. Don't be disheartened the first few times when you run on grass and can't match the times you run on the road it is more difficult, but wait until you do have a run on concrete after doing some training on grass, it seems so much easier and you'll be bounding along like Steve Cram (well maybe not but I'm sure you'll notice an improvement). Give grass a try it has really improved my training.