i'm more a fun-workout guy, i find that pushing my longboard for long distances trains my quads and the rest of my legs enormously + it's fun ! (learn to ride fakie as well so you can push with both legs)
and it also helps improve your balance on rails...
for full body strength i go bouldering/climbing
swimming is also great for overall endurance/strength + you can wrap up your session with half an hour or an hour on the divingboard practicing tricks and getting airtime :)
and another fun thing to do is slacklining (google it if you don't know it)
it's great for improving your core strength and balance + it's very much like rail skiing in terms of hopping on and off and keeping your balance + if you get the hang of it you can do some sweet tricks on it !