Changing careers at 12 years into a job, is it realistic? - what worked for you?

I want to move from bank teller to something with more stability. I have good customer skills and I am comfortable with spreadsheets.

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

I began with informational chats, then a short online course, then a related entry-level role. It took about 6 months.