Changing careers at 12 years into a job, is it realistic? (update)

I want to move from sales associate to something with more stability. There are 12 people counting on me, so I am trying to be careful. 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 settled down once I kept a simple log of every call and form.