I started running for the first time ever about 6 weeks ago and the first run was awful - 6 minutes round the block, nearly died! But I persevered and got up to running for 20 minutes quite easily. But I'm stuck there now! I try to run 3 times a week and just can't get past 20 minutes. I know I've made good progress from my first run but I really want to get better. Any tips before I give up and go back to my sofa?!