He says you need the attitude to not start with the question, "What do I want to do?" but with the question, "What needs to be done?" Mr. Drucker's second question places focus on the interests of the company or project and on execution.
Don't just try asking the question. Make it a habit. Write the question
"What needs to be done?"
across the top of your notebook. Post it under the clock on the wall where you have your project meetings. Add it to your email signature. Make a sport out of it; see how many times in the course of your project meetings you can ask and answer, "What needs to be done?"
Finish each conversation with someone making a reliable promise to do what needs to be done.