Use concrete actions instead of inflated labels. Saying you prepared a checklist for the next shift tells people more than calling yourself an exceptional operational leader. Clear description lets the listener understand the contribution without asking them to accept a grand claim.
Write a short account of the situation, what you did, and any result you can support. Mention other people's contributions where relevant. You can be proud of useful work while keeping its scale accurate. Confidence grows from being able to explain the example, not from making it sound larger.