Burnout is often ambition spending energy it never budgeted.

Burnout rarely comes from laziness or lack of ambition. It comes from plans made without an energy budget, where the hours are counted and the capacity is assumed to be infinite. Every project gets added to a life that was already full, and the shortfall gets paid out of sleep, health, and relationships until the account is empty. The ambition was not the problem, the accounting was.

Before you take on the next thing, ask what it will cost in energy rather than in hours, and what is coming out to make room. If nothing is coming out, the answer is probably no.