Over the past couple of months, Jess has been attending sessions at The Running School in central London.
At each session the instructors have been working with Jess to improve her running technique with the aim that she stay injury-free as her marathon training progress.
Along with injury prevention it will also help strengthen her arms and legs, and increase her speed as well as her confidence in her running.
Take a look at her before and after video to see how her running technique has changed in such a short space of time. Amazing!