In Steven Covey's bestseller The 7 Habits of Highly Effective People, he saves what may be the most important habit for last. 

His seventh habit is "Sharpen the saw", and it can be summarised like this:

"If lumberjacks spent all their time sawing down trees but never once paused to sharpen their saws, they’d soon have such dull tools that they couldn’t fell a single tree. Similarly, if you never pause to take care of yourself, any gains in effectiveness you achieve will be short-lived, for you’ll soon exhaust yourself and won’t be able to maintain any of the good habits you’ve developed. 

That’s why “sharpening your saw” is essential for lasting effectiveness in each of the four key dimensions of your life: To stay physically fit, you need to exercise regularly, eat healthily and avoid undue stress. Your spiritual health also contributes to lasting effectiveness. This could mean praying or meditating, or simply regularly reflecting on your own norms and values. To stay mentally healthy, read plenty of good books, avoid spending too much time in front of your television screen and make time for your own writing in some form – be it letters or poetry or a diary.

Organising and planning things are also good exercises to keep your mind sharp and fresh. Last but not least, it’s important to take care of your social and emotional health by deliberately seeking to understand others, building positive relationships with them and working on projects that help improve their lives." (Summary from Blinkist)

Sharpening your spiritual saw means having a way to release stress, tension, anxiety and fatigue so the best version of you is the one in the driving seat most of the time. It means getting your mind in a state where it can react calmly under pressure, foresee many issues before they happen, have access to creative solutions and an ability to see opportunities where others see problems and threats. 

Sharpening your saw is so important because it will determine the quality of everything else you do. How do you keep your saw sharp? 

For those who haven't read it, the other habits are: 

1. Be proactive
2. Begin with the end in mind
3. Put first things first
4. Think win/win
5. Seek first to understand, then to be understood
6. Synergise

If some of these sound like overused concepts, it's only because this book has become so influential in the 30 years since its first release. Well worth a read.