Changing careers at 4 years into a job, is it realistic? - 5 months and counting

After 4 years as a sales associate I am thinking about moving into a different field. I do not usually post, so bear with me. I have a little time and a small budget for training. How did you start?

Thanks for writing this out. I went through something close to it 5 months ago, and it got easier once I kept a simple log of every call and form.