In a hierarchy of goals (purposes, objectives, targets, missions), the questions:

“Why am I doing this?”,
“What am I doing?”,
“How am I doing this”?,

are answered by:

the parent, or next goal up, in the hierarchy,
the current goal in the
the children, or next goals down, in the hierarchy,


The top level-goal (mission) in a given hierarchy has no “why” answer within the current framework. That answer comes from the purposes of the system in which the current goal hierarchy is contained. The mission statement is an expression of that higher-level purpose within the current context.