on we go , on we go , up hills , grabbing onto plants sometimes to pull myself up , and down hills , holding on to rocks to keep my balance now and then , the scent keeping well clear of anywhere easy it might be to walk , like the flatter parts down by the road or riverbank , and i 'm coughing and sometimes stumbling and as the sun starts to show itself there comes a time when i ca n't , when i just ca n't , when my legs crumple beneath me and i have to sit down .