What you were thinking of before was not a KR. It was an individual task to achieve the KR. There is so much bad KR advice out there. Making each KR an individual task is exactly how OKRs (well its one way of doing that) fail in companies.
The objective you had was kinda fine even though it certainly has the connotation of volunteering in person. But if you just make the KRs something like "increase time I help the community by 5 hours per week" then the individual tasks can adjust without making you fail the OKR. Well sure you really envisioned doing a full "work day" each week for habitat for humanity. Covid hit so now you volunteer at the "teens in trouble hotline" for 8 hours a week. KR checked!
The objective you had was kinda fine even though it certainly has the connotation of volunteering in person. But if you just make the KRs something like "increase time I help the community by 5 hours per week" then the individual tasks can adjust without making you fail the OKR. Well sure you really envisioned doing a full "work day" each week for habitat for humanity. Covid hit so now you volunteer at the "teens in trouble hotline" for 8 hours a week. KR checked!