Anything goes dude, you use almost your entire body to surf, just do some basics like before you go to bed do some krunches or situps and pushups. And then in the morning run like a mile or so, it’ll definetly keep you in shape. Good Luck!
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This what I do during summer but when school starts I stop because I play soccer too and that’s enough of a workout for me.

Swimming is of course the oblivious one, but any cardio vascualar and aerobic fitness training will help, I have seen paddling trainers advertised in the mags, but I have never known anyone who has used them. The other option is to just go for a paddle regularly, after all what trains you better for paddling, than paddling itself?

Another thing that alot of good surfers do is yoga, or some other streching/suppleness training, as the positions you find yourself in when surfing can be quiet extreme.

A final item that is not really fitness related but also helps improve your surfing is balance training, so grab a skateboard or balance board and just cruise about on it and have fun.
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Core, upper body & lower body.

Core will help with balance. Like yoga, sit up’s

Upper body: push up’s, pull up’s, swimming or just simply getting on your board and paddling.

Lower body: Running, cycling. Having strong legs will help with your maneuvers.
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Swim.
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Balance trainers!

They help your surfing a lot, and at the same time strengthen your core and legs.
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