The Paradox of the Heap is also known as Sorites Paradox (sorites being the Greek word for heap). It's a concept that you'll hear many talk about in wealth generation which can be applied to health and fitness.
The thought experiment goes like this:
Suppose someone comes along and puts a large pile of sand on a table. They then proceed to move the sand, one grain at a time to another location on the table. There's no way the new collection of sand is a heap. It is simply a collection of grains of sand. However, if one were to diligently pursue this transfer process, the inital heap would no longer be a heap. Furthermore, there would come a time when transferring just one grain would effectively create a new heap.
In Gretchen Rubin, author of Better than Before: Mastering the Habits of our Everyday Lives, refers to this paradox as the "One Coin Problem". Giving a man one coin at a time does not make him rich, but you will reach a point where one coin will cause him to be classified as "rich".
Examples of this paradox exist in fitness, where daily efforts amount to barely anything, until one day results magically appear. The act of lifting weights does not make you stronger, but do it enough times and allow for adequate rest, and you will become stronger. No single meal will make you ripped or toned, but three months of clean eating will cause you to transform your body.
This is the paradox that we all struggle with. Your health is made up of tiny choices made throughout the day. No choice is inherently good or bad and will have little effect on your health. However, the series of choices you make, the habits you have formed, the environment you have created for yourself - each make up little grains could potential grow your heap.
The journey is a struggle and a grind, but some days, when you look back, you'll realize that you've made progress.
Gretchen Rubin on adopting new habits.