Changing careers at 17 years into a job, is it realistic? - 11 months and counting

After 17 years as a data-entry clerk I am thinking about moving into a different field. There are 17 people counting on me, so I am trying to be careful. 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.