First, congratulations. A lot of mixed emotions come along with a major career change. The best way for you to manage the stress depends, in part, on your preferences and experiences.
There is a quote that comes to mind by William James - "The greatest weapon against stress is our ability to choose one thought over another." Meditation can be a useful practice for reducing the stress that comes with change and helping us to recognize when we can choose "one thought over another.".
Other practices to consider include spending time in nature - walking or hiking, moving your body through other activities you enjoy like biking, running, yoga, or tai chi. Hot or warm baths, a cup of tea... Indulging in those things on a regular basis that bring you joy - art, for instance, can help to center you during transition periods and bring you to a calmer place.
Eating healthy and well, getting good sleep, and maintaining connections with those who are dear to you can have a significant positive impact on your stress levels as well.
Feel free to reach out to me if you have follow up questions.
All the best,