I chose something small to start with. Making a conscious choice to catch myself going 100 mph, and slow down, just slow down. For instance, getting ready for work, choosing my clothes for the next day, having things set out , doing the morning routine... and catch myself..slow down. Or chose something along that line... something you usually do in the morning that will set the pace for the rest of the day... For me, it was more being conscious of when I was doing it... slow down.... repeat....
I found that how I started my day set the pace on how I was going to be all day.. it takes conscious practice...I kept a 'slow down' journal during that time... teaching myself when I needed to pay attention, and to also be aware of progress... some of us are just wired to be driven.
So pick something small, manageable, and practice...catch yourself, slow down, repeat.... you will soon find that there are other things you are automatically slowing down with. Be flexible, don't beat yourself up... be proud that you have recognized this as something that is not working for you anymore.. and don't be upset with yourself if you find that you have gone three whole days at full tilt boogie.... just start again where you are.
Don't know if I made myself clear, but first and foremost, be kind to yourself as you are learning a new way to do things that will help in the long run.... hope some of this helped.... sending you hugs, reminding you to be good to yourself !!!