Changing careers at 16 years into a job, is it realistic? - any advice?

After 16 years as a procurement assistant I am thinking about moving into a different field. I have good customer skills and I am comfortable with spreadsheets. How did you start?

I took a small pay cut for a year, and it was worth it for the growth afterwards.

You likely have more transferable skills than you think. Write down what you did, not what the job title said.