Thanks that is specific rather than annual

A certificate at an event is not what people report valuing.

Recognition in volunteer programmes concentrates in an annual event with certificates and a speech. It is well intentioned and it is not what volunteers describe as making them feel valued, which is consistently something smaller and closer to the work.

What they report is being told specifically what their contribution achieved, by somebody who saw it. That the thing they sorted meant a delivery went out, that the person they sat with had nobody else that week. Specificity is what distinguishes thanks from politeness.

The other form is being asked. Volunteers who are consulted about how something should be done experience that as a stronger signal of value than any amount of formal appreciation, because it treats their judgement as worth having.

Formal recognition still matters for some people, particularly where it can be used externally, and the useful version is a reference or a written statement of what they actually did rather than a generic certificate.

There is a form of recognition that costs nothing and is consistently undervalued, which is asking somebody's opinion about how the service should work. It signals that their judgement is regarded as worth having, which is a stronger statement than gratitude and frequently produces a good idea as well.