Marathon runners understand endurance intuitively. It takes time and effort to get ready to run a long race. Running a marathon is not something that you can do overnight. 

Typically, a runner will make a months-long plan of action and follow it religiously to build up the stamina needed to run the race. There is an understanding that there will be aches and pains and ups and downs along the way. This is all part of the plan and necessary to get across the finish line in time. Even during the event, marathon runners ensure to maintain a certain pace, going overboard and running too fast can result in burn out and not completing the race.

In investing you must identify the aches and pains that are a normal part of investing. Financial markets are volatile and see ups and downs all the time. You must recognize how much of this volatility you are able to endure in the normal course of investing. Making a plan of action and sticking to it through these ups and downs is key to building long term wealth. Not getting too carried away with new fads and themes in investing is also crucial when considering the end goal that is trying to be achieved.

But, every once in a while, there is an extremely low probability event that occurs which can have a dramatic impact on your financial life. This could be from a black swan event like the 2008 financial crisis or it could be something far more personal like an accident or a job loss. 

Being prepared for these unforeseen shocks prevents you from getting wiped out. This is why having an emergency fund and appropriate insurance are critical tools that can protect you financially when you most need it. They help to tide over any income loss and give protection from serious wealth erosion due to unforeseen circumstances. This is one of the main reasons why these tools should not be looked at from the perspective of getting returns but more from the perspective of giving you endurance to stay in the race.