My $0.02, having been a PM for many years: Read Cracking the PM Interview [1] (for an overview of the job, not the actual interview tips) and The Lean Startup [2] (for general philosophy). 35 is a great age for a PM, especially since PM's often start elsewhere -- maturity is a plus here. I'd say there are 3 main ways into it -- as an engineer, who starts to do PM-type stuff on a team where there's no PM. As a designe…
I recommend you build and release your own product start to finish. This helps you get exposure to parts you got to avoid in your engineering role.
I see product management as a producer role which includes the successful release and iteration. This is best learned by doing and if you don’t have a team, you be the team.