Aside from the obvious - i.e. keeping my skills sharp - I recently realized continuing to teach adult ed classes has a few ancillary benefits, for me and others.
* Because one of the colleges has begun sending me out to retirement communities, teaching folks older than I about music continually reminds me to be on the lookout for premature hardening of my musical arteries. Each time a participant declares something they don't like as "noise", my musical antenna becomes more receptive to stuff I've similarly dismissed. (Look for a near-future post where rap gets a new look from yours truly - title will likely mention eating crow)
* On the non-musical side, regular teaching gigs force me to pay more attention to my grooming in post full time work land. This piece probably benefits my wife more than I, but I'm reasonably sure my daughter is also relieved her Dad doesn't closely resemble Grizzly Adams - on a good day - whenever a teaching assignment is imminent, especially if a get-together with her boyfriend's family is also on the calendar.
What in your life provides unforeseen benefits? Are the benefits mostly for you? For others? Both?