A retired skill can become a gift when its owner is free to choose where it is useful.

Expertise does not expire with the job. What changes is that nobody is buying it any more, and that turns out to be a kind of freedom: the accountant helps a neighbor make sense of a letter, the nurse knows what to ask at the appointment, the teacher gives an afternoon to someone struggling. The skill is unchanged and the choosing is now entirely yours.

If you have stepped back from work, pick one small place your knowledge would help and offer it on your own terms. Keep it bounded, so it stays a gift rather than a post you never applied for.