Changing careers at 15 years into a job, is it realistic? - what worked for you?

After 15 years as a home health aide I am thinking about moving into a different field. I have read a lot of threads here and could not find my exact situation. My family is supportive but nervous. How did you start?

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