This seems like a pretty weak list to be called a "Toolkit". I think burnout is like another major issue: boredom, and both share the common trait that by the time a manager is aware of it, it is too late to address. Tips like "be positive" and "express gratitude" are table-stakes to being a decent team member; they're not nearly enough for a manager to to proactively address burn-out. Increasing headcount or reducing scope are rarely in the control of a direct manager. Nothing here attempts to address the underlying causes of burnout that include: boring & repetitive work with no slack in the schedule and a persistent expectation of fighting fires and noisy, immediate delivery.