Depending on the reasons for your DEC, have you considered cadets? Could be volunteer, CI, possibly even CIC. Bring experience to the table, limited hours, familiarish environment. Physical requirements are pretty light. And a chance to bring light and understanding to young minds. And bring some light into yours.
Not quite “casual”, but since the focus appears to be doing something occupational rather than financial, its in the volunteer spectrum without being strictly volunteer.
Of course, if you don’t like kids, teaching or have serious PTSD, it might not be for you, but cadets is crying for people to run QM, do Admin or even run units. Having a clue about how the Regs do things might help with understanding the bureaucracy and red tape, leading to a net benefit to the unit, and a sense of accomplishment because, DEC or not, you’re the guy who gets things done. On a limited work schedule.