A keystone habit is a behavior or routine that naturally pulls the rest of your life in order.
I first heard about this idea in Charles Duhigg's book, The Power of Habit. When I started looking at my own life, I began to notice a few routines that led to better behaviors elsewhere.
For example, a funny thing happens when I lift weights...
When I work out, I want to eat better. Even though I could reward myself with chocolate bars and ice cream, I feel like eating healthy, unprocessed foods.
When I start working after exercising, I seem to be more productive. My mind is clearer and my writing is crisper. Thoughts flow easily.
And at the end of the day, I fall asleep quickly. I tend to sleep more and feel fresh when I wake up.
And when I don't exercise, I see the opposite effect. I'm more prone to eating junk food. I stay up later, get distracted more easily, and I waste time on unimportant tasks. Stress builds and I start to feel tension in my back.
In other words, fitness is the keystone habit that puts the rest of my life in place. I don't have to think about eating better. I don't have to force myself to focus on getting things done.
I'm not always on top of my game, but on the days I train everything seems to come a little bit easier. Exercise naturally pushes me towards my best self.