Fixing /data/db not found error in MacOS X when starting MongoDB

How to fix /data/db not found error in Mac OS X when Starting MongoDB

So, you are a mobile app developer or a web application developer. You decided to try MongoDB as the database because you heard a great thing about it. You installed successfully. Alright, so far so good. But you execute mongod command, you see the following error in your MacOS X Terminal when you start MongoDB for first time.