I am thinking about taking up surfing. It seems difficult though
A surface water sport like surfing will always be difficult unless you practice everyday 
Who even thought up such a sport?
The native peoples of the Pacific many thousands of year ago, when they first embarked on sea.
Is it a competative sport or in the Olympics?
It can be, in Olympics there are surfing competitions that include knee boarding, and surf matting
What is surf matting?
It is when a surfer riding inflatable mats goes through many relays.