If you want to exercise to get in shape for surfing start with your feet. The feet help provide shock absorption, balance, force, control, power, flexibility, strength and agility to your ride.
So how do you get started? Most surfers have already done some benefit to your feet by walking barefoot on sand or smooth rocks... not so sure about the coral.
All of the following exercises can be done in bare feet.
Start by rolling a tennis ball under your foot. This helps awaken the soft connective tissue (fascia). Do not put your full weight on the foot being rolled. Work up to using more pressure and using a lacrosse ball or golf ball. Roll the ball with a little more pressure under the heels, balls and outer edge of your feet and less pressure in the arches and toes. Spend at least 1 minute on each foot.
Try to pickup sand/small rocks with your toes. Once you have accomplished this task try to fling the objects with your toes.
Lift your foot off the ground and write in the air your favorite surfing spot. Pretend your toes are a pen and your ankle is a wrist.
With your feet apart keep your heels stationary and push/drag the balls of the feet and toes outwards away from center. When they are out as far as they can go (duck footed) lift the front of the feet off the ground (heels stationary) and bring them back to neutral. 10-15 times.
With your feet apart keeping your heels stationary lift the balls of your feet and toes up and go outwards. When they are out as far as they can go bring the front of the feet down and drag them back to neutral. 10-15 times.
Press your four small toes down and try to raise your big toe. This is a difficult exercise and when you first attempt it you can lightly hold down your 4 toes with your hand. Sometimes if you tap or lightly push the arch of your foot it helps. 10-15 times.
Press your big toe down and try to raise you 4 little toes. Again, you can start by spreading your toes as far apart as you can. Hold for 3-5 seconds 5-10 times.
Rock feet back and forth from heels to toes. 15 - 20 times.
Walk on your heels and then walk on the balls of your feet.
Lift your big toe and feel your arch go up. Bring toe down and try to keep the arch raised for a few seconds.
Stand on a step with the balls of your feet on the step and your heels hanging over the edge. Slowly use the whole front of the foot to rise up as high as you can then drop your heels down as low as you can get them. 10 -20 times.
If it hurts do not do it! This includes if you feel pain in your knees as you work your feet. See a foot doctor for pain, surfer's toe and fungal issues.