Product Strategy and Product Operations at Zendesk. Led Help Centers for advertising products at Google. Expertise in Strategy, Product Management and Design for B2B SaaS companies.
I did it gradually by beginning to do the things product managers I worked with did. One task and skill at a time while I was in a role in an adjacent team. That also helped me see which skills were transferable, in some cases skills other product managers didn't have.
What those skills and tasks are depends how you define the product manager role you want. Product Management can mean many different things depending which industry and company you're in. It covers a broad spectrum from deeply technical roles to more marketing and sales oriented ones.