Originally Posted by shygrneyzs
When my Dad retired he ran into the same problem - time on his hands and not quite prepared for it all. He did his regular passions like fishing and hunting and camping but wanted something more. He got involved in woodwork. He made tables, bookcases, cabinets, cut patterns for wood crafts and sold them.
I don't know your skills so it is hard to say what would match for you. But finding a hobby that uses your skills is an easy place to start. Expanding your skills and learning something new are avenues for you.
You would be a great mentor, considering your background. But I also recognize that sometimes a person wants to go into a different area after retirement. Whatever you choose, wishing you the very best.