Chances are you will break, but with time and patience you can only get better.
I had this challenge once with a friend. He told me being a nerd I had the worst fitness ever; after a good debate why workout doesn't matter he told me I wouldn't last 5 minutes on a thread mill- The very next day I ran(more like walking very fast) for 45 minutes. Of course I was nearly collapsing after that. By my point was never to run 45 minutes. It was to run the next 3 minutes without giving up, slow down when its overwhelming and keep going at a steady speed and aim to not give up for the next immediate 3 minutes.
I've tried everything else. Drinking sugar cane juice, eating a snack, sipping tea. Nothing has worked apart for that 'Don't give up in the next x minutes' strategy. I'm lead to believe this is common in sports too, Test cricket for that matter is believed that, can be excelled by players who can play from a session to session. Just focus on playing this session well.