Changing careers at 12 years into a job, is it realistic? (St. Louis)

After 12 years as a bookkeeper 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. How did you start?

I began with informational chats, then a short online course, then a related entry-level role. It took about 5 months.