If you are starting to hunch or lean forward, there are a few techiques that you can try. The first is to use the MolyFit checklist which can be found here: https://www.molyfit.co.uk/molyfit-checklist/

I would then advice you to have a look in my book A Better You in Later Life. I wrote this to help strengthen and improve not only the core muscles, but all the muscles in the body responsible for keeping you upright. This can be found here: https://www.molyfit.co.uk/better-you-book/

Finally, please have a look at this 10-minute exercise routine specifically for improving posture in Parkinson’s:

Try and take the exercises that work for you and practice them daily, adding them into your routine.