f**k the gym, all you need is trainers and motivation to run. Im shit at this, but watch these people do it near me. Find a f**k off massive hill, thats fairly long, starting at the top, run down it. go back up to a set point you make on it. repaeat but as you go up next time, increase the distance by say 5m if the hill is big enough. keep increasing till you fall over or pass out. do that for couple of weeks and you should notice a difference in stamina, leg strength and breathing. Getting a road bike may help you get fit to.