Execution is not someone else's job
There's a common misperception that the top exec in a company conceives the strategy, and execution happens below. Let's first define “strategy” and “execution,” the former is about making choices and the latter acting on them, i.e., people making decisions about what to do and what not to do.
Strategy work is as a series of interconnected choices: What’s our winning aspiration? Where will we play? How will we win? What capabilities do we need to win? What systems do we need?
No matter where you are in the company as leader, the choices are the same; they are all where to play/how to win strategy choices.
While traditional definitions hold that strategy happens at the top and execution is done below, a more useful definition is that strategic choices are made throughout the organization and the responsibility for execution lies at the top.