The number e, also known as Euler’s number, is a mathematical constant approximately equal to 2.71828, and can be characterized in many ways. It is the base of the natural logarithms. It is the limit of ⁿ as n approaches infinity, an expression that arises in the study of compound interest. Wikipedia
Euler’s number is used in everything from explaining exponential growth to radioactive decay.
One question about a regular daily practice of mindfulness (or any other practice) is if the result is compound? Are the outcomes exponential? What do you think?