I love surfing mostly in ocean. I think the waves in lakes or rivers are too small
Is it even possible to surf in a lake or river?
Yes it  can also be found in lakes or in rivers in the form of a standing wave or tidal bore.
Huh. I never knew that. How long does it take to learn how to surf?
You can learn it if you utilize artificial waves such as those from boat wakes and the waves created in artificial wave pools.
Well I don't have those tools at the ready to be able to utilize them lol
As long as you are involved in riding a wave, regardless of whether the wave is ridden with a board or without a board, and regardless of the stance used, you are surfing
How would someone surf without a board?
The native peoples of the Pacific, for instance, surfed waves on alaia, paipo, and other such craft. Those are some examples
I can't pronounce any of those words lol