I paddle board on my days off.
That's great exercise for your arms since you are using them to swim while lying, standing or kneeling on a paddleboard.
Yeah, but I get tired quick.
You can also try stand up paddle surfing or stand up paddleboarding. 
Thanks, i'll give it a try. What are the origins of paddle boarding?
In the early 1930s, Thomas Blake was given credit for the paddleboard construction. 
Wow, he must of been a championship paddler. Did Thomas Blake break any paddle boarding records?
Not sure he paddleboarded, but he drilled holes in the board and then covered them, making it the first hollow board.