Changing careers at 18 years into a job, is it realistic? - 16 weeks in

After 18 years as a medical assistant I am thinking about moving into a different field. This is my first time dealing with any of this. I have a little time and a small budget for training. Has anyone made a similar move?

Thanks for writing this out. I went through something close to it last year, and it got easier once I kept a simple log of every call and form.