I'll join in offering congratulations to you for your business success
and in actually retiring (if only temporarily perhaps) at age 51.

In addition to the SCORE web site which someone mentioned,
I'd suggest you look at http://www.iesc.org if you haven't already.
You mentioned enjoying travel: IESC
("International executive service corps") sends people to other countries.
It is unpredictable whether you will be offered any assignments,
but you might be offered several. My father had two in Brazil for a total
of nearly a year, and a shorter one in Mexico, in the 70s and 80s.
He and my mother thoroughly enjoyed the experiences.

I suppose there may be other organizations that also
do the same kind of thing.

hirundo