Thanks for the encourgement guys! The book I have been reading is called Run for life: the real womans guide to running. by sam murphy. I am really impressed with it so far, my favourtie bit is how it explains how your body uses stored energy, its heaps interesting. The formula to work out your ideal running weight is, allow
'45.36kg for the first 1.52m of your height, and a further 2.25kg for every 2.5cm above 1.52m. For example, if you are 1.67m tall, your ideal running weight would be 45.36 + (6*2.25) = 58.92kg.' (sam murphy pg 27. Run for life).
She goes on to say that its pretty conservative, and that many healthy runners exceed this margin. But still reckonmends being within 3kg of it before you begin to run. Its just got me really spooked how much force is transferred through your joints with each step, she says on pg 80 that a 60kg woman exerts a force equal to between 20,000 and 40,000kg through your legs and spine every minute of running! I've had a good pair of runners for ages awhile now, i got them last time i was going to start running so i had them properly fitted by an expert,but of course hardly used them, but my reward for when i get to 30mins of constant jogging is definantly going to be a new pair!