I use the lion as an image for focus: choose a target, give it your effort, then recover. Being busy all day tells me very little about what actually moved forward.
The point is that ten or twelve uninterrupted hours should not automatically be your definition of a good working day. Ask what the effort is meant to produce.
Choose a task with a visible finish: send the proposal, solve one customer problem, or complete the first version of a page. “Be busy with the business” does not tell you when you have achieved anything.
Decide what can wait while you work. Close the unrelated tabs and leave the next idea somewhere you can return to it. If your role involves being available to others, agree a realistic period of focus instead of pretending you can disappear all day.
When that work block ends, look at the result. Did you finish the task, discover a real obstacle, or spend the time reacting? Use the answer to plan the next block.
Rest belongs in this picture too. You do not need to turn every pause into another productivity technique. The metaphor is an invitation to be deliberate with effort. Aim at something, do the work, and make space to stop. Judge the day by useful progress rather than by how exhausted you can make yourself.
Related reading and sources: focus