The One Thing by Gary Keller. This book teaches the science of higher focus and productivity by identifying what's most important to you.
Here are my 3 big lessons you can use to produce your best work and achieve your goals.
Identify your one thing. The key to success is identifying the one thing that will make everything else easier or unnecessary. By focusing on that one thing, you can achieve extraordinary results.
Use the 80/20 rule. The majority of your results come from a minority of your efforts. The 80/20 rule states that 20% of your actions will result in 80% of your outcomes. Focus on the 20% that will make the biggest impact.
Use Time-block in your day. To ensure you have enough time to work on your one thing, it's important to time block your day. Schedule your most important tasks during your most productive hours and eliminate distractions during those times. This will help you make progress towards your goals consistently.

In summary, your productivity hits the sky once you know what is the one task that will make the maximum impact on your day and in general, your life. By focusing on your one thing, you can achieve incredible results and unlock your true potential.