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?
"alii" (kings). He lightened his redwood replica ("olo" were traditionally made from "wiliwili" wood) by drilling it full of holes, which he then covered, thus creating the first hollow board, which led to creation of the modern paddleboard. Two years later, using this same , board, Blake won the Pacific Coast Surfriding Championship, first Mainland event integrating both surfing and paddling. Blake then returned to Hawaii to break virtually every established paddling record available, setting and records that stood until
Paddleboarding
Paddleboarding participants are propelled by a swimming motion using their arms while lying, kneeling, or standing on a paddleboard or surfboard in the ocean. This article refers to traditional prone or kneeling paddleboarding. A derivative of paddleboarding is stand up paddleboarding also called stand up paddle surfing. Paddleboarding is usually performed in the open ocean, with the participant paddling and surfing unbroken swells to cross between islands or journey from one coastal area to another. Champion paddlers can stroke for hours and a race is only a warm-up for