Kaizen is the main concept behind 200WaD.
It's a Japanese philosophy of self-improvement that can be summed up in one sentence: destinations are reached one step at a time.
A goal is a journey.
Let's pretend you want to climb the Everest. You can do it in one go, or you can stop at every basecamp along the road.
If you do the former, chances are, you won't make it to the top.
If you take the latter path, you might stumble and fall, but you will have the opportunity to adjust and figure out what works best for you. You will also enjoy the road, rather than focusing too much on the destination.
Those little steps will eventually compound, and culminate into you reaching the top of the world.
Kaizen acknowledges the fact that no one can tell you how to reach a destination when the only road leading to it is unknown. Similarly, our lives are all different.
When you break down a goal into manageable chunks, it gets easier to track the progress, see what works and what doesn't, and adjust accordingly.
On the contrary, the surest path to failure is to take on too much at once, not being able to process the workload, and thereby commit philosophical suicide.
It doesn't mean you should perform at 10% of your capabilities every day as not to wear yourself out.
It means you should dedicate your full attention to each task to accumulate momentum.
Do not despair. Results will come, but how can you hope to climb the mountain if you are not capable to stick to a single step every day?